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We demonstrated a stable passively Q-switched fiber laser operation at 1531.57 nm using a double-transition metal MAX phase TiNbAlC saturable absorber. The prepared saturable absorber's modulation depth, saturation intensity, and non-saturation loss are 1.75%, 0.089 MW/cm 2 , and 32.81%, respectively. Using the TiNbAlC saturable absorber within an erbium-doped fiber laser ring cavity, stable Q-switched pulses with a central wavelength of 1531.57 nm, and a 3-dB bandwidth of 1.43 nm are acquired. The minimum pulse duration and the maximum single pulse energy are 3.18 μ s and 51.56 nJ, respectively. Furthermore, the maximum repetition rate is 37.9 kHz with a signal-to-noise ratio of 50 dB. Our results indicate that double-transition metal MAX phase TiNbAlC can be an excellent saturable absorber candidate for an ultrashort pulse fiber laser. [ABSTRACT FROM AUTHOR]

Laser-induced breakdown and subsequent plasma are produced in ambient air in the proximity of an aqueous surface using a Nd:YAG Q-switched laser at 1064 nm with a pulse width of 9 ns and a delivered focused input energy of 170 mJ. The distance between the focal point of a 10 cm convex lens and the aqueous surface is 4 mm with laser propagation perpendicular to the surface. Using an intensified CCD camera attached to a 1-m spectrometer, spatial and wavelength-resolved plasma emission data are obtained for delay times after breakdown ranging from 50 ns to 10 μs with a gate window typically 5 ns. Plasma electron density is determined by applying Lorentzian fitting and FWHM extraction to three Stark-broadened spectral lines: N II 3P-3Do multiplet (593.85 nm), Hα (656.27 nm), and the Na D doublet (589.00 and 589.59 nm). One-dimensional spatially resolved measurements of the total emission intensity and electron density are obtained by binning the camera image along the laser axis in intervals of 250 μm and are reported as a function of time from 50 ns to 10 μs. Two plasmas are ignited from a single laser pulse; one from laser breakdown at the water surface and the other a few nanoseconds later from laser-induced air breakdown at the focal point of 4 mm above the water surface. Comparisons between the evolution of the air plasma near and far from the water surface are presented along with data for the water surface plasma itself. [ABSTRACT FROM AUTHOR]

Simultaneous measurements using two Intensified Charge-Coupled Device (ICCD) cameras with two bandpass filters on laser-induced air plasma have facilitated the illustration of a two-dimensional temperature distribution within the plasma. In each pixel, the intensity captured by the ICCD cameras could replace the intensity measurements using a spectrometer in the two-line ratio method for temperature measurement. The plasma was produced by a 532 nm pulse from a Q-switched neodymium-doped yttrium aluminum garnet laser. The two ICCD cameras with the two bandpass filters simultaneously captured the plasma to measure emission intensities at two wavelengths. The two-line ratio method using N II lines was applied in each pixel to examine the two-dimensional temperature distribution. Two laser energies and focal lengths were utilized to ensure spatially and temporally consistent temperature results considering the characteristics of the plasma temperature at the experiment conditions. The signal-to-noise ratio increased with increasing the incident energy and decreasing the focal length. The highest temperature was observed at the high incident energy and the short focal length. The location in the plasma with the maximum temperature varied over time. The temperature significantly reduced with time at the long focal length and low incident energy. The plasma temperature was measured using the two-line ratio method with a spectrometer. Average emission intensity images at the two wavelengths were used to examine the plasma temperature. The results of the three temperature measurement methods were compared to evaluate the accuracy of the methods. Generally, in the three methods, the temperature changes were similar along the x-axis of the plasma. The temperature difference between the two-filtered imaging method and the spectrometer was between 1 and 7%. The temperature difference between the average image method and the spectrometer was between 1 and 10%. The two-filtered imaging method simultaneously captures spectral emissions at two wavelengths and hence effectively shows a two-dimensional temperature distribution. [ABSTRACT FROM AUTHOR]

Lasers of low-coherence have attracted the attention of researches since the first publications on this topic in the 1960s and up to the present time. Low-coherent quasi-continuous LD-pumped Nd:YVO4 and Nd:YAG lasers with ≈ 1 ms pulses of 1064 nm radiation at 10 Hz repetition rate and 21–47 W output power are reported. Spatial coherence of laser radiation was determined by the contrast C of speckle patterns, C = 0.02 - 0.1. These Nd-lasers optical efficiency is in the range 20%–50% (depending on the coherence level). The low coherence was obtained at multimode lasing in a plano-spherical resonator near its stability limit. Experimental data are commented on using the calculated dependences of the number of laser modes and the degree of coherence on resonator configurations and pump spot sizes. The achieved contrast values C < 0.03 are below the level of human perception and correspond to the level of spatial coherence typical for thermal sources of radiation. Possible applications of the developed low-coherent multimode Nd-lasers and directions for further research are discussed. [ABSTRACT FROM AUTHOR]

This paper demonstrates a laser diode double-ended pumped Yb: YAG rod regenerative amplifier (RA) with an average power of 37 W, which substantially exceeds the performance of previously reported bulk Yb: YAG medium RAs. Compared to other bulk Yb: YAG medium RAs, we have introduced several enhancements in thermal management, such as employing a double-ended pump to reduce the temperature gradient inside the crystal, and the cooling efficiency is significantly enhanced by designed heat sink. As a result, the thermal effect is effectively suppressed. The system attains high average output power and power stability (RMS = 0.56%) at a pulse repetition rate of 400 kHz. In addition, the output beam maintains excellent quality even under varying high pump powers, demonstrating an M 2 consistently below 1.1. [ABSTRACT FROM AUTHOR]

Q-switched fiber lasers have become reliable light sources for generating high-energy pulses, which can be passively modulated by saturable absorbers with excellent nonlinear optical properties. The composite combining Ag and MXene exhibits a broadband nonlinear response and high modulation depth, making it a promising candidate for saturable absorbers in pulsed lasers. Herein, we demonstrate a Q-switched Tm:Ho co-doped fiber laser centered at 2 µm, where the Ag/MXene composite serves as a saturable absorber to generate pulses. The typical spectrum, pulse train, and radio frequency spectrum of Q-switched pulses were observed, in which the 60 dB signal-to-noise ratio was higher than that of 2 µm Q-switched fiber lasers based on other materials, demonstrating the stability of the output pulses. Additionally, the long-term stability of the laser was evaluated over 2 h, where the well-maintained central wavelength and output power also indicated the robustness of the Q-switched laser. Furthermore, the influence of the pump power on the parameters of Q-switched pulses was also investigated, which is conducive to control the output characteristics of lasers. Specifically, the pulse width of the Q-switched pulse decreased, while the repetition rate, output power, and single pulse energy all increased with the increase in pump power. These experimental results demonstrate the ability of Ag/MXene as a saturable absorber and show its potential for generating high-performance pulses in ultrafast lasers. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) violet phosphorus (VP) plays a significant role in the applications of photonic and optoelectronic devices due to its unique optical and electrical properties. The ultrafast carrier dynamics and nonlinear optical absorption properties were systematically investigated here. The intra- and inter-band ultrafast relaxation times of 2D VP nanosheets were measured to be ~6.83 ps and ~62.91 ps using the pump–probe method with a probe laser operating at 1.03 μm. The nonlinear absorption coefficient βeff, the saturation intensity Is, the modulation depth ΔR, and the nonsaturable loss were determined to be −2.18 × 104 cm/MW, 329 kW/cm2, 6.3%, and 9.8%, respectively, by using the Z-scan and I-scan methods, indicating the tremendous saturable absorption property of 2D VP nanosheets. Furthermore, the passively Q-switched Nd:YVO4 laser was realized with the 2D VP nanosheet-based SA, in which the average output power of 700 mW and the pulse duration of 478 ns were obtained. These results effectively reveal the nonlinear optical absorption characteristics of VP nanosheets, demonstrating their outstanding light-manipulating capabilities and providing a basis for the applications of ultrafast optical devices. Our results verify the excellent saturable absorption properties of 2D VP, paving the way for its applications in pulsed laser generation. [ABSTRACT FROM AUTHOR]

Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) is successfully employed to determine the chemical composition of brass samples using the LIBS technique. The sample is irradiated with a Q-switched Nd: YAG laser with a pulse width of 5 ns to generate laser-induced plasma (LIP) on the sample surface. The time evolution spectra were recorded from the surface of the brass sample only with an accumulation of five laser shots to get one LIP spectrum. Time-resolved LIP spectra have been utilized to identify the most appropriate time window (where the plasma is optically thin and in local thermal equilibrium) suitable for CF-LIBS implementation. Stoichiometric ablation is also demonstrated for metallic brass samples with the aforementioned laser in the present study. To obtain definitive quantitative information from LIP, the characterization of the plasma, i.e., spectral line intensity, spectral line broadening, electron number density, and plasma temperature, has been analyzed in this paper. Based on two different CF-LIBS algorithms, the brass sample composition was determined and found to be in good agreement with the certified results. This paper also compares and contrasts both strategies, as well as discusses their place and importance. The results of the present manuscript illustrate the potential applicability of CF-LIBS for yielding precise and accurate compositions of brass. [ABSTRACT FROM AUTHOR]

Nickel diselenide (NiSe2) microspheres were synthesized using a chemical vapor deposition (CVD) method, and their nonlinear optical properties were investigated. The prepared NiSe2 exhibits good nonlinear characteristics, demonstrating a high modulation depth and a low saturation intensity. Then the NiSe2 was used as a saturable absorber device and integrated into a 1.5 μm erbium-doped fiber laser to generate Q-switched pulse. By optimizing the cavity dispersion and adjusting the polarization state within the cavity, the single pulse tunable Q-switched pulse, Q-switched mode-locking pulse and quasi-mode-locked pulse based on NiSe2 saturable absorber are realized. Among them, the signal-to-noise ratio of the quasi-mode-locked pulse is as high as 68 dB, which proves that the resulting pulse has high stability. The findings of this study suggest that NiSe2 SA devices have the potential to be developed as highly efficient candidates for ultrafast photonics and can find extensive applications in nonlinear optical fields. [ABSTRACT FROM AUTHOR]

The peculiar nonlinear optical responses of two-dimensional (2D) materials endow them highly attractive for photonics applications. This review systematically discusses the performance of pulsed lasers employing 2D materials as their modulation device. First, it is crucial to categorize 2D materials that can act as saturable absorbers, encompassing a range of substances such as Graphene, Black Phosphorus, Topological Insulators, MXene, and even heterojunction. Furthermore, a thorough investigation is conducted to analyze the performance indexes to study the nonlinear characteristics of 2D materials in the pulse generation. Especially, the focus is on the 1.5 μ m band ultrafast lasers utilizing 2D materials. This paper also provides a comprehensive analysis of the obstacles and prospects in 2D materials preparation, and their utilization in the pulse laser systems. [ABSTRACT FROM AUTHOR]

Mid-infrared (MIR) pulsed lasers operating in the ∼3 μm region play a crucial role in various applications, including molecular spectroscopy, ultrafast molecular imaging, and laser-assisted surgery. Despite recent advancements in MIR gain platforms, a notable technological challenge remains in the absence of an effective optical Q-switch. Here, a remarkable optical Q-switch in the 3 μm region based on a Dirac semimetal PtTe2 saturable absorber is realized. By modulating the surface state of PtTe2, the pulsed laser exhibited an increase in average power, escalating from 521 to 588 mW, accompanied by a significant decrease in pulse width from 368 to 187 ns. Nondegenerate pump–probe measurements showed that the recombination rate of the photocarrier in thinner PtTe2 nanoplates was effectively accelerated, primarily attributed to the substantial increase in surface state density, leading to better saturable absorption performance. As the thickness of the PtTe2 nanoplates decreases, the nonsaturable loss decreases from 12% to 3%, while the modulation depth increases from 6% to 12%. The enhanced ultrafast nonlinear absorption enables flexible modulation of saturation absorption parameters, which endows high-performance MIR pulsed laser generation. [ABSTRACT FROM AUTHOR]

Ultralow-noise microwaves are essential in a wide variety of scientific and technological applications, such as metrology, radars, and communications. Here, we propose and demonstrate a scheme for generating an ultralow-noise microwave signal using a Brillouin optical frequency comb (OFC), which is based on the stimulated Brillouin scattering in combination with a frequency-shifted optical injection locking mechanism. The generated two intra-cavity Brillouin lasers are used as the intra-cavity pump for the eventual formation of the OFC and thus the microwave signal via the cascaded four-wave mixing process. Exploiting the cascaded narrowing effect in the Brillouin cavity assisted by the frequency-shifted optical injection locking, the proposed microwave signal source exhibits ultralow phase noise. Experimental results show that the phase noise of the microwave signal is equivalent to below −115 dBc / Hz for a 200-GHz carrier at 10 kHz offset. The system can work in stable operation without the need for any active feedback loop. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrated a high-performance light-emitting diodes (LEDs)-side-pumped Nd: glass rod laser with high average power at a repetition rate of 20 Hz. The LEDs-side-pumped lasers have the special advantages, like rapid switching, low thermal effects, and large mode volume, which could be effectively solve the thermal effect induced distortions of radiation and tensile stresses in Nd: glass. Under the quasi-continuous wave (QCW) operation conditions, the maximum single pulse energy of laser at 1053.75 nm was up to 211.5 mJ with a pulse duration of 1.176 ms, corresponding to the maximum output average power of 4.23 W. In the active Q-switched regime, the highest peak output power was 1.84 kW with a pulse duration of 364 ns at a repetition rate of 1 kHz, corresponding to the beam quality factor of M2 = 7.5. To the best of our knowledge, this is the first demonstration of an LED-pumped actively Q-switched Nd: glass rod laser with watt-level output reported so far. [ABSTRACT FROM AUTHOR]

Buried depressed-cladding waveguides were fabricated in 0.7-at.% Nd:Ca3Li0.275Nb1.775Ga2.95O12 (Nd:CLNGG) and 7.28-at.% Yb:CLNGG disordered laser crystals grown by Czochralski method. Circular waveguides with 100 μm diameters were inscribed in both crystals with picosecond (ps) laser pulses at 532 nm of 0.15 μJ energy at 500 kHz repetition rate. A line-by-line writing technique at 1 mm/s scanning speed was used. Laser emission at 1.06 μm (with 0.35 mJ pulse energy) and at 1.03 μm (with 0.16 mJ pulse energy) was obtained from the waveguide inscribed in Nd:CLNGG and Yb:CLNGG, respectively, employing quasi-continuous wave pumping with fiber-coupled diode lasers. The waveguide realized in RE3+-doped CLNGG crystals using ps-laser pulses at high repetition rates could provide Q-switched or mode-locked miniaturized lasers for a large number of photonic applications. [ABSTRACT FROM AUTHOR]

The utilization of boron carbide nanoparticles (B4C) as a saturable absorber (SA) for generating pulses by a fiber laser operating in Q-switched mode is the subject of our investigation, the findings of which are presented. This was accomplished by combining boron carbide nanoparticles (B4C-NPs) with polyvinyl alcohol (PVA) to form a thin-film-based SA. This SA was then placed within an erbium-doped fiber laser (EDFL) in a ring cavity configuration to enable passive Q-switching operation. The modulation depth of the B4C-SA was 2.3%. Stable Q-switching laser operation was accomplished with a pump power of 180 mW and central wavelength of 1561 nm by producing laser pulses with a pulse duration of 15.27 µs and pulse repetition rate of 31.6 kHz. A comparable pulse energy, which was attained at the maximum pump power of 275 mW, was approximately 2.61 nJ. The radio-frequency spectrum was examined to verify the pulse stability. The study showed a signal-to-noise ratio of 35 dB. These results expand the potential of B4C-based saturable absorbers, making them strong contenders for innovative photonic devices. [ABSTRACT FROM AUTHOR]

The heightened awareness of ethnic dermatology aligns with the growing prevalence of skin of color communities globally, where hyperpigmentation disorders pose a common dermatological challenge. Effectively addressing dermal pigmentation is challenging due to its resistance to conventional therapies and its association with impaired quality of life. This underscores the need for effective treatments and a thorough grasp of laser advancements. A relevant literature search spanning the last 7 years across the PubMed database reveals core studies, challenges, and the evolution of laser technologies tailored for various forms of congenital and acquired dermal hyperpigmentation in skin of color. This comprehensive review explores the mechanisms, applications, and recommendations for pigmentary laser technologies, highlighting the key role of Q-switched lasers in their established millisecond/ nanosecond forms and emerging picosecond lasers, fractional non-ablative and ablative lasers, Intense Pulsed Light, etc. The summary of evidence includes studies on dermal melanocytosis (nevus of Ota and Hori's nevus), tattoos, acquired dermal macular hyperpigmentation, etc., and also entities with mixed epidermal–dermal components, such as melasma and post-inflammatory hyperpigmentation. The review offers valuable insights for clinicians to make informed decisions based on diagnosis, skin type, and the latest technologies to optimize results and minimize complications, especially in darker Fitzpatrick skin types. In their five-year study with 122 Indian patients, the authors applied specific laser combinations for diverse dermal melanoses, including tattoos, dermal/mixed melasma, acquired dermal macular hyperpigmentation, and dermal nevi. Substantial pigmentation reduction, subjectively assessed by both physicians and patients, was observed across all groups. A one-way ANOVA indicated a significant difference in mean improvement scores across various pigmentary conditions (F = 3.39, p = 0.02), with melasma patients exhibiting a significantly higher improvement score than tattoos (p = 0.03). The results affirmed the safety and efficacy of sequential laser therapy for dermal pigmentation in skin of color, advocating for flexibility in approach while maintaining the rationale behind the laser sequences. Despite advancements, challenges persist, and gaps in the current literature are identified. In conclusion, this summary highlights the ongoing pursuit of optimal protocols in dermatological laser treatments for dermal melanoses, offering valuable insights for future research and clinical practice. [ABSTRACT FROM AUTHOR]

This study investigates the impact of laser pulse energy (500 mJ/pulse) on silver, gold, and silver@gold NPs and deposited on porous silicon. The objective is to assess their effects on structural, optical, morphological, and electrical properties, aiming to identify optimal conditions. Nanoparticles are produced through the technique of pulsed laser ablation in liquid (PLAL). This involves employing a Q-switched Nd: YAG laser operating at a wavelength of 1064 nm and pulse duration of 10 ns. X-ray diffraction (XRD) analysis validates the crystalline development of (core–shell) NPs, evident from the presence of XRD peaks corresponding to Au and Ag NPs. Morphological analysis reveals excellent adhesion between NPs and the substrate (PS), enhancing structural stability. UV–vis spectra demonstrate a localized surface plasmon resonance (LSPR) band within the 420–540 nm range. This band shifts from two peaks to one with increased gold content. A comparison of the photoluminescence emission spectra of porous silicon and Ag@Au NPS/PS at room temperature. The porous silicon exhibits an extreme PL emission band broadening centered at a visible wavelength of 620 nm (2.033 eV), which reveals the excellent quality of the PS structure. Photodetector measurements highlight maximum responsivity for the Ag@Au/PS photodetector. These Ag@Au NPs show promising attributes for high-performance photodetector applications. [ABSTRACT FROM AUTHOR]

Raman spectroscopy and laser-induced breakdown spectroscopy (LIBS) are powerful tools for molecular and elemental analysis, respectively. Their combined application, however, is challenging due to the differences in the signal generation and detection characteristics. This note proposes three experimental schemes for the simultaneous application of Raman and LIBS for gas-phase diagnostics. Ring-cavity optical pulse stretchers facilitate shaping suitable pulse pairs from a Q-switched laser that enables the quasi-simultaneous detection of the Raman and LIBS signals on a single detector. [ABSTRACT FROM AUTHOR]

Background: Pigmented lesions are largely benign and may lead to extreme distress. Various light and lasers may be used to treat pigmentation, often Q‐switched lasers are considered the method of choice, while intense pulsed light (IPL) devices may offer a less invasive treatment with a shorter downtime. Objective: The purpose of this study is to evaluate the safety and efficacy of a narrowband IPL module for the treatment of pigmented lesions. Methods: A retrospective study of 20 patients with pigmented lesions underwent treatment with an IPL module. Treatment was assessed by blinded evaluation of clinical photographs using a GAIS scale of 0–10, as well as through patient satisfaction ratings on a scale of 0–10. Throughout the treatment, pain levels and adverse events were monitored. Results: The mean GAIS score was 7.55 ± 1.15 (mean ± SD), and the mean patient satisfaction score was 7.3 ± 1.26 (mean ± SD). There was a strong positive correlation between GAIS and patient satisfaction scores (r = 0.83), and no significant difference between them (p‐value = 0.516). The number of treatments did not significantly affect GAIS and patient satisfaction scores (p‐values 0.364 and 0.126). Additional positive unexpected outcomes were improved skin firmness and reduced wrinkles. Conclusion: The results of the study indicate that the IPL module is both safe and effective in treating pigmented lesions and may have the potential to stimulate collagen production. [ABSTRACT FROM AUTHOR]

Dielectric metasurfaces are highly sought‐after since they have found a variety of linear and nonlinear applications. Here, a novel transmission modulation is presented for pulsed laser generation by directly exploiting the enhanced Kerr effect from a periodic array of silicon nanodisks. The Mie resonance of the unit cells enhances the Kerr effect of the silicon material and is redshifted by the latter, so that the transmission of the metasurface at the working wavelength is strongly modulated (the observed modulation depth is above 3% under moderate exciting power). By inserting the fabricated metasurface as a self‐modulator into a ring cavity fiber laser, stable Q‐switched pulse laser output is achieved with a duration of 1.4 µs and a repetition rate of 60 kHz. This work opens a door for ultra‐thin low‐loss dielectric metasurfaces to efficiently shape the operation of pulsed lasing based on their enhanced nonlinear effects and flexible propagation manipulation. [ABSTRACT FROM AUTHOR]

Background: Facial hypermelanosis is a major cosmetic issue that causes severe social embarrassment and psychological pain, particularly among Asians and dark-skinned individuals. Aim: This study assesses the safety and effectiveness of Q-switched 1064/532 nm nanosecond/picosecond lasers in removing benign hypermelanosis in dark-skinned individuals, evaluating the possible associated side effects. Material and methods: A total of 30 participants (80% females and 20% males) with Fitzpatrick skin types IV–V–VI who presented superficial benign hypermelanoses on the facial and décolleté area were enrolled. All patients underwent to one to two laser treatment sessions with a 1064/532 nm Q-switched laser system. Three months after the final laser session, results were assessed by comparing before- and after-treatment photos and using a quartile scale for lesion clearance (4-point Investigator Global Assessment scale). Results: All patients observed global improvements in their pigmented lesions: 53% of patients achieved excellent clearance, 30% of patients achieved good to moderate clearance, 10% of patients achieved slight clearance, and 7% of patients did not respond to the therapy. No serious adverse event occurred. Photos showed the clinical improvement achieved at 3 months follow-up. Conclusions: The Q-switched 1064/532 nm laser proved to be a key tool for treating benign hypermelanosis in all skin types, including dark-skinned persons. [ABSTRACT FROM AUTHOR]

We assess the temperature stability requirements of unseeded Nd:YAG lasers in lidar systems for atmospheric temperature profiling through the rotational Raman technique. Taking as a reference a system using a seeded laser assumed to emit pulses of negligible spectral width and wavelength-drift free, we estimate first the effect of the pulse spectral widening of the unseeded laser on the output of the interference filters, then we derive the limits of the allowable wavelength drift for a given bias in the temperature measurement that would add to the noise-induced uncertainty. Finally, using spectroscopic data, we relate the allowable wavelength drift to allowable temperature variations of the YAG rod. We find that, in order to keep the bias affecting atmospheric temperature measurements smaller than 1 K, the Nd:YAG rod temperature should also be kept within 1 K. [ABSTRACT FROM AUTHOR]

In this study, silver-tungsten oxide core–shell nanoparticles (Ag–WO3 NPs) were synthesized by pulsed laser ablation in liquid employing a (1.06 µm) Q-switched Nd:YAG laser, at different Ag colloidal concentration environment (different core concentration). The produced Ag–WO3 core–shell NPs were subjected to characterization using UV–visible spectrophotometry, X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive spectroscopy, electrical analysis, and photoluminescence PL. The UV–visible spectra exhibited distinct absorption peaks at around 200 and 405 nm, which attributed to the occurrence of surface Plasmon resonance of Ag NPs and WO3 NPs, respectively. The absorbance values of the Ag–WO3 core–shell NPs increased as the core concentrations rose, while the band gap decreased by 2.73–2.5 eV, The (PL) results exhibited prominent peaks with a central wavelength of 456, 458, 458, 464, and 466 nm. Additionally, the PL intensity of the Ag–WO3-NP samples increased proportionally with the concentration of the core. Furthermore, the redshift seen at the peak of the PL emission band may be attributed to the quantum confinement effect. EDX analysis can verify the creation process of the Ag–WO3 core–shell nanostructure. XRD analysis confirms the presence of Ag and WO3 (NPs). The TEM images provided a good visualization of the core-spherical shell structure of the Ag–WO3 core–shell NPs. The average size of the particles ranged from 30.5 to 89 (nm). The electrical characteristics showed an increase in electrical conductivity from (5.89 × 10−4) (Ω cm)−1 to (9.91 × 10−4) (Ω cm)−1, with a drop in average activation energy values of (0.155 eV) and (0.084 eV) at a concentration of 1.6 μg/mL of silver. [ABSTRACT FROM AUTHOR]

BACKGROUND: Onychomycosis is a fungal infection of the nail unit that affects a large patient population globally. Onychomycosis, or tinea unguium, has a benign chronic clinical course; however, it can cause complications in certain patient populations suffering from diabetes and peripheral vascular disease. As nails grow slowly, onychomycosis requires a lengthy treatment plan, and choosing appropriate treatments can be challenging. There are a variety of treatment modalities available for patients including topical, oral, laser, light therapy, procedures such as avulsion and matrixectomy, supplements, over-the-counter medication, and plasma therapy that can be used as monotherapy or in combination for patient satisfaction. OBJECTIVE: We sought to review treatment options for onychomycosis, taking into consideration the efficacy, side effect profiles, practicality of treatment (adherence), and costs to help healthcare providers offer ethically appropriate treatment regimens to their patients. METHODS: A literature search was conducted using electronic databases (PubMed, Embase, Medline, CINAHL, EBSCO) and textbooks, in addition to the clinical experiences of the authors and other practitioners in treating onychomycosis, and a summary of the findings are presented here. RESULTS: Although topical (efinaconazole, tavaborole, ciclopirox), oral (terbinafine, itraconazole), and laser (1064nm Nd:YAG lasers, both shortpulsed and Q-switched lasers, carbon dioxide lasers, and the diode 870, 930nm) are the current Food and Drug Administration (FDA)-approved treatments for onychomycosis, they are just a fraction of available treatment options. New and emerging therapies including new topical and oral medications, combination therapy, photodynamic light therapy, procedural, supplements, over-the-counter medication, and plasma therapy are discussed in our review. DISCUSSION: Onychomycosis has high reinfection and recurrence rates, and the treatment remains challenging as treatment selection involves ethical, evidence-based decision-making and consideration of each individual patient's needs, adherence, budget, the extent of quality of life discomfort, and aesthetic goals, independent of potential financial benefits to the clinicians. [ABSTRACT FROM AUTHOR]

Broadband sum-frequency conversion of multiline (~ 60 spectral lines within ~ 5–6 μm wavelength interval) Q-switched CO laser emission in an AR-coated ZnGeP2 crystal was experimentally studied by application of both single-pass and double-pass optical schemes. The maximum conversion efficiency in the double-pass scheme reached ~ 10% that is 2.5 times higher than one obtained in the same optical scheme with an uncoated ZnGeP2. The spectrum control of frequency converted radiation by changing angles of incident and reversed CO laser beams in the ZnGeP2 crystal was implemented within the wavelength range from 2.52 μm up to 2.92 μm. The maximum spectrum width of 0.35 μm was obtained with the double-pass scheme when the angle of the laser beam incident on the crystal and the angle of the deflected reversed laser beam were −4.0° and 1.0°, respectively, the spectral bandwidth being three times broader than one obtained with the single-pass scheme. [ABSTRACT FROM AUTHOR]

Antimonene has attracted much attention due to its excellent characteristics of high carrier mobility, thermoelectric properties and high stability. It has great application prospects in Q-switched lasers, laser protection and spintronics. At present, the epitaxy growth of antimonene mainly depends on molecular beam epitaxy. We have successfully prepared antimonene films on silicon, germanium/silicon substrates for the first time using electron beam evaporation coating and studied the effects of the deposition rate and substrate on the preparation of antimonene; film characterization was performed via confocal microprobe Raman spectroscopy, via X-ray diffraction and using a scanning electron microscope. Raman spectroscopy showed that different deposition rates can lead to the formation of different structures of antimonene, such as α phase and β phase. At the same time, it was found that the growth of antimonene is also affected by different substrates and ion beams. [ABSTRACT FROM AUTHOR]

Two dimensional (2D) ternary chalcogenides, a significant class of optoelectronic materials, exhibit distinctive structures and possess exceptional physical and chemical properties. In this study, a novel 2D ternary chalcogenide, Ta2NiTe5, is synthesized using the liquid‐phase exfoliation technique to create a high‐quality saturable absorber (SA). The nonlinear optical characteristics of the prepared Ta2NiTe5 nanosheets, ranging from 500 nm to 3.0 µm, are investigated using the P‐scan and open‐aperture Z‐scan methods. Furthermore, the stable passively Q‐switched lasers based on the Ta2NiTe5‐SA device are realized with a minimum pulse width of 326 ns, 2.18 µs, and 850 ns at 1.0, 2.0, and 3.0 µm wavelengths, respectively. The findings not only provide further evidence of the promising potential of 2D ternary chalcogenides as an SA for the achievement of broadband pulsed lasers, but also pave the way for promoting their potential applications in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Background: With nearly 50% of the population in the United States, Italy, and Sweden tattooed with at least one tattoo, the demand for its removal has risen by 32% since 2011. Traditional removal methods, such as Q‐switched (QS) laser‐based tattoo removal, can be lengthy, requiring up to 20 sessions. Aim: This study presents a retrospective clinical evaluation of seven short‐pulsed QS, dual‐wavelength Nd:YAG laser, as an efficient alternative, that can potentially reduce the number of sessions needed as calculated by a founded scale. Methods: The QS modality delivers high‐intensity pulses in four wavelengths, ideal for removing multicolored tattoos, of which two were used. We studied 11 patients who underwent 3–8 treatments (average 5.09) every 2–3 months. Each tattoo was assessed using the Kirby–Desai scale, considering the following factors: location, Fitzpatrick skin type, ink amount, layering, scarring, tissue changes, and tattoo color. Follow‐ups were conducted after 6 months and at 4–5 years following last session. Results: The long‐term follow‐up presented a significantly higher tattoo removal efficiency than the short‐term follow‐up (p < 0.001), indicating a sustained process of ink breakdown and elimination. Notably, the actual number of treatments were significantly lower than that predicted by the Kirby–Desai scale (average 5.09 vs. 9.9, p < 0.001). No severe adverse events were reported. Conclusions: In conclusion, the QS Nd:YAG laser offers a safe and effective alternative for tattoo removal, requiring fewer treatments than initially expected. [ABSTRACT FROM AUTHOR]

In this work, we proposed a mechanical exfoliation technique to compose a saturable absorber (SA) from MAX phase chromium aluminum carbide (Cr2AlC). The performance of a passive Q‐switched erbium‐doped fiber laser (EDFL) based on Cr2AlC‐SA was experimentally demonstrated. The optical properties of SA showed appropriate nonlinear absorption, with a non‐saturable absorption of 92.5%, and saturable absorption of 1.2%. The proposed EDFL was investigated using 50:50 and 80:20 output couplers (OCs). At 167 mW pumping power and 3 dB OC, the EDFL produced pulses with 2 μs width, and 163 kHz repetition rate. Moreover, with 80:20 OC, the EDFL produced shorter laser pulses with 1.46 μs width, and 135.2 kHz pulsing rate. The results reveal that the higher repetition rate with high energy can be obtained with a 3 dB coupler, while narrower pulse width is achieved with an 80:20 OC. [ABSTRACT FROM AUTHOR]

TiB2 nanoparticles with a bandgap of 0 eV were prepared, and the corresponding nonlinear optical response at 2.85 μm was investigated. Employing a TiB2 as a saturable absorber, a 2.85 μm pulsed Er:Lu2O3 crystal laser with an average output power of 1.2 W was achieved under a maximum pump power of 9.51 W. Laser pulses with durations of ~203 ns were delivered at a repetition rate of 154 kHz, which corresponds to a pulse energy of ~7.8 µJ and a peak power of 39.3 W. As far as we know, the result represents the highest average output power from all Q-switched Er:Lu2O3 crystal lasers. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes a wireline serial link transceiver for on‐package die‐to‐die links based on 12‐nm fin field‐effect transistor (FinFET) technology. The link is crucial for improving the computational performance of larger systems built from chiplets. To achieve high pin/energy efficiency and prevent traditional single‐ended signaling disadvantages, the transceiver adopts single‐ended ground‐reference signaling (GRS) to transfer information. To precompensate for the frequency‐dependent loss, retain the advantages of GRS, and avoid the disadvantages of traditional AC‐coupled equalizer, the transmitter in the transceiver adopts a DC‐coupled switched‐capacitor charge pump equalizer that can transmit GRS and its equilibrium value can be adjusted according to the channel attenuation. This paper proposes a method for timing de‐skew using digital control delay lines to eliminate the timing skew between data and the clock. In addition, this paper presents a duty cycle corrector to avoid duty cycle distortion, with an adjustment range of 44.5% to 52% and a power dissipation of only 30 μW. The transceiver has an area of 1.016 × 0.676 mm2, including one clock lane link and four data lane links. At a nominal 0.8‐V power supply voltage, the aggregate eye‐opening of the measured 25 Gb/s data on an organic substrate channel with an attenuation of −2.2 dB over 6 mm is 0.675 UI, with a bit error rate (BER) of less than 10−12 and an energy efficiency of 1.01 pJ/bit. [ABSTRACT FROM AUTHOR]

A gas sensor utilizing V2O5/Pd thin films has been successfully created by pulse laser deposition on porous silicon substrate, demonstrating rapid response times and superior sensitivity for detecting gases at low temperatures. The investigation of sensor response, selectivity, and stability demonstrates the impressive sensing capabilities of the thin films. Vanadium pentoxide films doped with palladium (V2O5/Pd) are fabricated through pulsed laser deposition technique, with varying laser pulse energy (600, 800, and 1000) mJ/pulse, for the purpose of sensing applications related to Hydrogen Sulfide (H2S) and Nitrogen Dioxide (NO2). The ablation procedure entails the utilization of a Q-switched Nd:YAG laser that operates at a specific wavelength of 1064 nm. The laser system exhibits pulse duration of 10 ns and a repetition rate of 1 Hz when operating on a porous silicon n-type Si (111) substrate. The X-ray diffraction, UV–Vis Spectroscopy, Raman scattering, Photoluminescence spectroscopy, and field emission-scanning electron microscopy techniques were employed to investigate the crystal structure, optical structure, and morphological properties of the V2O5/Pd NPs. As the energy of the pulse laser grows, the presence of well-defined peaks in the V2O5/Pd thin film indicates an enhancement in its crystalline structure. The size of the surface grains exhibit an augmentation, accompanied by an increase in the energy gap, leading to an elevated level of homogeneity. This study aimed to evaluate the influence of Pd on the development kinetics of vanadium pentoxide nanoparticles. The findings of this investigation demonstrated that the addition of Pd resulted in several notable effects, including improved sensitivity, reduced operational temperature requirements, and the capacity to maintain high sensitivity levels even at room temperature. [ABSTRACT FROM AUTHOR]

Mid‐infrared (MIR) pulsed lasers operating at 2–5 µm have important applications in communication, sensing, and medicine. However, the lack of robust MIR saturable absorbers (SAs) remains a major obstacle. Here, a semiconductor material cadmium oxide (CdO) film with high laser‐induced damage threshold (800 nm, 134 mJ cm−2) and broadband saturable absorption (2.0–3.9 µm) is investigated. The effective tuning of the nonlinear optical response of CdO is demonstrated by adjusting the carrier concentration via a tungsten (W)‐doping scheme. The saturable absorption is improved and carrier relaxation process is accelerated after increasing the W‐dopant level. Based on these findings, the robust CdO‐SAs with customizable parameters are realized and Q‐switched lasers with decreasing pulse width from 372 to 254.3 ns are obtained at 2 µm. The design flexibility provided by CdO opens up a large parameter space that enables the continuous improvement of compact and high‐performance MIR ultrafast lasers. [ABSTRACT FROM AUTHOR]

Background: The unappealing appearance of skin in macular amyloidosis (MA) interferes with the patient's quality of life, and treating the condition has been challenging. Aims and Objectives: To compare the efficacy and safety of 15% trichloroacetic acid (TCA) peel, 35% glycolic acid (GA) peel, and Q-switched Nd-YAG Laser in MA. Materials and Methods: Open, prospective study was conducted over 2 years, where after fulfilling the criteria, randomization was done into three groups. Group A: 15% TCA peel; Group B: 35% GA peel; Group C: Q-switched Nd-YAG Laser. Procedures were repeated at monthly intervals for six sittings. On each visit, patients were scored on the following parameters: color score, visual analog score (VAS), physician global assessment (PGA) scale, subjective improvement, and adverse effects. Results: A total of 75 patients (25 patients in each group) completed the treatment. The mean age of study-population was 35.68 ± 9.8 years, with female to male ratio of 11.5:1. The mean change in color score (1.68) was more by Group A, followed by Group C (1.4), followed by Group B (1.16). Similar results were noted by subjective improvement, VAS, and PGA. Adverse events were more in Group A, followed by Group C, followed by Group B. No patient showed permanent adverse events. Conclusion: TCA-peel showed superior results over Nd-YAG laser and glycolic-acid peel. TCA-peel being cost-effective with excellent acceptability should be considered a treatment modality. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate a Q-switched erbium-doped fiber laser (EDFL), which is passively produced by using a saturable absorber (SA), which is fabricated by mechanical exfoliation of MAX phase molybdenum titanium aluminum carbide (Mo2Ti2AlC3). Physical and optical properties of the SA are experimentally studied. The optical properties showed a good nonlinear absorption where the saturation intensity is 0.65 MW/cm2, with 40% of non-saturable absorption and 17% of modulation depth. The proposed EDFL is investigated using two output couplers (OCs) with split ratios of 50:50 and 80:20, respectively. For pumping power of 142 mW and coupling ratio of 50%, the proposed EDFL produced pulses with a pulse energy of 69.60 nJ, pulse width of 2.97 μs and repetition rate of 90.09 kHz. Besides, with coupling ratio of 20%, the EDFL can generate a pulse train with a pulse width of 1.91 μs, repetition rate of 77.64 kHz, and pulse energy of 89.52 nJ. [ABSTRACT FROM AUTHOR]

Pulsed laser ablation in liquid (PLAL) has demonstrated the superiority in synthesizing many free-contamination metal oxides as well as nanostructured metals. In the present study, ZnO and Al-doped ZnO colloidal nanoparticles were synthesized by pulsed laser ablation in a water using a Q-switched Nd: YAG laser beam (1064 nm, and pulse with 700 mJ) focused on the surface of the Zn target. According to X-ray diffraction (XRD) results, ZnO NPs and aluminum doped-zinc oxide (AZO) colloidal nanoparticles were found to be of the crystalline hexagonal wurtzite-type. UV–Vis spectrophotometer analysis of the fabricated ZnO NPs and AZO NPs has demonstrated high absorption spectra in the ultra-violet regime, while their band-gap energies were assessed at 3.1 eV and 3.3 eV, respectively. Scanning electron microscope (SEM) images of the formed ZnO NPs revealed high agglomerates of semispherical NPs with an average size of about 48 nm whereas when ZnO NPs doped with Al, their morphology modified to nanorods with dimensions of about (124 nm × 90 nm), indicating the presence of Al in the synthesized ZnO nanoparticles. The I–V characteristics for ZnO NPs/Si and AZO NPs/Si heterojunction structure were evaluated under dark and light conditions. The produced device displayed strong photovoltaic characteristics, indicating that it could be applied to optoelectronics. These findings demonstrate the suitability of Al-doped ZnO produced in water using the laser ablation technique for UV detectors. Therefore, nanosecond laser ablation in liquid is a great way to prepare different nanostructures materials that can be used in a variety of fields and an efficient and flexible way to create nanoparticles with adjustable size, shape, and features. [ABSTRACT FROM AUTHOR]

LD end-pumped passively Q-switched a-cut Nd:YLF/Cr:YAG/c-cut YVO4 Raman laser is investigated for the first time, and SRS processes of 895 cm−1(A1g), 821 cm−1 (B1g) and 264 cm−1 (B2g) modes are realized. Raman laser output power, temporal, spectral and polarization features are studied, and unusual phenomena of Raman laser output are observed for the first time. The maximum efficient Raman conversions of 895 cm−1 (A1g), 821 cm−1 (B1g) and 264 cm−1 (B2g) modes are achieved with the linearly polarized direction of Ep to be about 45 degrees to a or b axis of c-cut YVO4 crystal. The optical axis orientation of c-cut YVO4 crystal significantly affect Raman laser spectra and polarization features. With experiments and analysis in-depth, these anomalies are attributed to optical axis direction deviation of c-cut YVO4 crystal. These findings can help design c-cut YVO4 multi-Raman mode lasers of high-performance, which have potential applications. [ABSTRACT FROM AUTHOR]

Two lasers of the same wavelength (1.06 µm) and various specifications were employed to synthesize silicon nanoparticles. The experimental data reveal the formation of stable silicon nanoparticles with different features such as UV-vis absorption, photoluminescence spectrum, Raman spectrum, Zeta potential, and SEM morphology. Theoretical simulations using COMSOL software were adopted to estimate the surface temperature distribution at the silicon surface and underneath. It is found that maximum temperatures of about (5700 K) and (4600 K) were generated when a Q-switched laser pulse of (10 ns) and fiber laser pulse of (127 ns) were used, respectively. While the recoil pressure at the silicon surface was (6.5*105 N/m2) and (1*103 N/m2) when Nd:YAG and fiber laser were used respectively. It found that increasing the laser energy for Nd:YAG laser and fiber laser power leads to a blue shift of the absorption spectra while the absorption intensity increases with the number of laser pulses and irradiation time. Raman spectroscopy for the prepared silicon nanoparticles was carried out. The Raman peaks for silicon nanoparticles reveal the formation of amorphous silicon. These peaks were observed at (482) and (475 cm-1) when Nd:YAG and fiber lasers were used to produce those nanoparticles. While the photoluminescence of the prepared silicon nanoparticles exhibits peaks at (457 nm) and (495 nm) for Nd:YAG and fiber lasers. The zeta potential reveals that silicon nanoparticle stability is greater for nanoparticles produced by fiber lasers (27 mv) than those produced by Nd:YAG lasers (17 mv) for three months. The corresponding silicon nanoparticle sizes refer to (3.8 nm) and (6 nm). Potential applications of silicon nanoparticles in optoelectronics and biological imaging can be conducted due to the controllable laser micro/nano machining process. [ABSTRACT FROM AUTHOR]

Introduction Dermatophytosis is a superficial fungal infection, which is limited to the fully keratinized layer of the skin (stratum corneum), nails and hair. A noticeable increase in number of patients with recurrent dermatophytosis was observed during the last few years, which differs from the classical mode of presentation of this infection by being symptomatic, more inflammatory, widespread, running a recurrent course and highly resistant to conventional treatments. Objective To evaluate the outcome of using Q-switched Nd:YAG laser (1,064-nm) as a new treatment modality for this vexing problem. Methods Twenty patients with thirty-three lesions of localized recurrent dermatophytosis with positive mycological study were collected, all of them were treated with Q-switched Nd:YAG laser (1,064-nm) 4 sessions, one week apart. The patients were followed up weekly until the end of first month, then monthly for 6 months. Results All patients showed excellent response to treatment with clinical cure rate of (100%). One patient had relapse (3.03%). Conclusion Q-switched Nd:YAG laser (1,064-nm) was found to be a safe and effective treatment of recurrent dermatophytosis that has been failed to respond to different types of systemic and topical antifungal drugs with excellent result and remarkable reduction in recurrence rate. [ABSTRACT FROM AUTHOR]

Thermal stability and phase transition rate are two important issues that restrict the engineering applications of phase change memories. In this paper, GeSb/Sb multilayer films were prepared by multilayer stacking, and their phase transition properties were investigated. GeSb/Sb multilayer films had higher crystallization temperature, better data retention, and lower resistance drift than pure Sb films, which indicated that they had excellent thermal stability and accuracy of resistance identification. The test results of X‐ray diffraction and atomic force microscopy showed that GeSb spacer layers could inhibit grain growth of Sb film layers, thus reducing the roughness and potential fluctuation of the film surface. X‐ray reflectivity experiments showed that the GeSb/Sb multilayer films before and after crystallization had small volume changes. The devices based on [GeSb(7 nm)/Sb(3 nm)]8 multilayer films could achieve reversible resistive transition operation between SET and RESET at a pulse width of 10 ns, showing satisfactory transition rate and operational power consumption. The low resistance drift and ultra‐fast phase transition speed make GeSb/Sb multilayer films one of the promising choices for phase change memories. [ABSTRACT FROM AUTHOR]

Background: The efficacy of fractionation is significantly impacted by the colloidal particles' spontaneous absorption of laser beam radiation. The classification of silver nanoparticles during fragmentation processing is regulated through the collection of a combination of laser pulses with wavelengths of 1064 nm and 532 nm. Aims and Objectives: This study presents an investigation of the efficacy of a plant extract in conjunction with the incorporation of supplementary silver nanoparticles, as well as the generation of smaller-sized silver nanoparticles using laser fragmentation.and then measure thier toxity on the blood. Results: Ag nanoparticles were synthesized using pulsed laser fragmentation on green tea AgNPs. The synthesis process involved the utilization of a Q-switch Nd:YAG laser with wavelengths of 1064 nm and 532 nm, with energy ranging from 200 to 1000 mJ. Initially, a silver nano colloid was synthesized through the process of fragmented of the Ag target using the second harmonic generation of 532 nm at various energy levels. The optimal energy within the selected wavelengths was determined in order to facilitate the ultimate comparison. Transmission electron microscopy (TEM) was used to determine surface morphology and average particle size, while a spectrophotometer was used to analyses UV light's spectrum characteristics. The measurements focused on the surface plasmon resonance (SPR) phenomenon. The absorption spectra of silver nanoparticles exhibit distinct and prominent peaks at wavelengths of 405 nm and 415 nm. The mean diameter of the silver nanoparticles was found to be 16 nm and 20 nm, corresponding to wavelengths of 1064 nm and 532 nm, respectively. Conclusion: As a consequence, there is a decrease in the range of particle sizes and a decrease in the mean size to lower magnitudes, resulting in a very stable colloid. This particular methodology has demonstrated considerable efficacy in the production of colloidal suspensions with the intended particle dimensions. Moreover, by the analysis of nanoparticles in human blood, no discernible alterations in the blood constituents were seen, indicating their non-toxic nature. [ABSTRACT FROM AUTHOR]

A 1089 nm Q‐switched laser has been successfully developed by using a neodymium‐doped fiber (NDF) as a gain medium and tin oxide (SnO2) material as a saturable absorber (SA). The SnO2 SA was obtained by embedding the compound into a polyvinyl alcohol (PVA) host polymer so that it can be easily integrated into an NDF laser (NDFL) configuration to modulate the cavity loss for pulsing operation. The laser output pulse duration and repetition rate changed from 6.7 to 4.2 µs and from 55.8 to 72.5 kHz, respectively, when the 808 nm pumping power increased from 160.0 to 252.7 mW. The laser exhibited a stable output since we recorded a signal‐to‐background noise ratio of 46.4 dB. We believe that this work is the first to address SnO2 as SA in an NDFL cavity. [ABSTRACT FROM AUTHOR]

This present study demonstrates the utilization of an electro‐optic modulator (EOM) to actively Q‐switch the pulses produced by an all‐polarization‐maintaining (all‐PM) erbium‐doped fiber (EDF) laser (all‐PM‐EDF laser). Electrical sine waves that produced steady microsecond pulses at 1552 nm were used to power the 10 GHz bandwidth EOM. By altering the frequency of the external modulation signal and the power of the input pump, the width of the pulses produced by the all‐PM‐EDF laser (4 μs) could be further decreased to 2.6 μs. When the modulation frequency of the all‐PM‐EDF laser was 15 kHz, the highest pulse energy that it produced (145 nJ) corresponded to its highest power output (52 mW). Therefore, sources of single‐polarization pulsed lasers that are significantly resistant to mechanical and temperature disturbances can be designed by merging the configuration of an all‐PM with an EOM. [ABSTRACT FROM AUTHOR]

We demonstrate a Ho:GdVO4 solid‐state laser pumped by a thulium (Tm)‐doped fiber laser at 1940nm. In continuous wave mode, a maximum output power of 6.1 W was obtained under the absorbed pump power of 31.9 W with the slope efficiency of 24.3% at the temperature of 18°C. The wavelength of output laser was 2048.53 nm with full width at half maximum of 0.2 nm. In Q‐switched mode, a maximum single pulse energy of 0.94 mJ was obtained with a minimum pulse duration of 7.3 ns at the pulse repetition frequency of 5 kHz, corresponding to a peak power of 129 kW and an average output power of 4.7 W. The beam quality factor of M2 was 1.01 under the maximum absorbed pump power. To the best of our knowledge, 0.94 mJ is the highest single pulse energy in single holmium (Ho) doped GdVO4 laser pumped by Tm‐doped fiber laser at 1940 nm, and 1.01 is the best beam quality factor of M2 in Ho:GdVO4 laser pumped by a Tm‐doped fiber laser. [ABSTRACT FROM AUTHOR]

In this study, the operation of compact diode‐pumped continuous wave and passively Q‐switched (PQS) Tm:YAlO3 (Tm:YAP) solid‐state lasers (SSLs) on the 3F4–3H6 transition is demonstrated. The first PQS operation of a mid‐infrared (mid‐IR) Tm:YAP laser at 1986.64 nm is realized with a Ta2NiS5‐based saturable absorber (SA). Under PQS mode, the Tm:YAP laser generated a maximum output power of 1.278/1.393 W with an optical‐to‐optical conversion efficiency of 8.81%/9.61%, corresponding to a narrowest pulse duration of 787/914 ns and a high repetition frequency of 187.932/151.115 kHz for 1.5%/2.5% transmittance of output coupler. The experimental results show that Ta2NiS5‐based SA is an excellent optical switch for diode‐pumped PQS mid‐IR SSL emitting around 2.0 μm. [ABSTRACT FROM AUTHOR]

A two‐dimensional titanium disulfide (TiS2) nanosheet film is prepared on a YAG crystal substrate. The saturated absorption behavior of TiS2 on the YAG substrate is investigated. Then, TiS2 is successfully employed as a modulation element to develop a Tm:YAG ceramic eye‐safe pulsed laser. With a 7.04 W absorbed pump light and a 3% transmission of output coupler, the greatest average optical power, and the least pulse width (PD) are 233 mW and 524 ns, separately. The pulse repeated frequency of 69 kHz is generated, while the single pulse energy (SPE) is 3.38 µJ. Based on the experimental results, TiS2 nanosheet films possess the practical value as saturable absorbers for 2.0 μm eye‐safe pulsed lasers. [ABSTRACT FROM AUTHOR]

In this paper, a compact diode‐pumped continuous wave (CW) and passively Q‐switched mode‐locked (QML) Tm:YAG lasers operation on the 3F4–3H6 transition is realized by using tantalum aluminum carbide (Ta4AlC3) phase ceramic (MAX) material as a saturable absorber (SA). The first stable QML operation of the mid‐infrared Tm:YAG laser at 2012.38 nm is demonstrated with a Ta4AlC3‐SA. A stable QML Tm:YAG laser was achieved when the absorption pumping power reached 14 W. Under QML mode, Tm:YAG laser generated a maximum average output power of 560 mW at 2012.38 nm with an optical‐to‐optical conversion efficiency of 4%, corresponding to a shortest pulse duration of 541 ps and a high repetition rate of 168 MHz. The experiment shows that Ta4AlC3‐SA is an attractive candidate for diode‐pumped CW and QML mid‐infrared all‐solid‐state lasers emitting around 2.0 μm. [ABSTRACT FROM AUTHOR]