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Ytterbium and rare earth ions (RE = Y, Gd, La) codoped CaF2-SrF2 single crystals (3 at% Yb,6 at% RE:CaF2-SrF2) were fabricated by temperature gradient technology (TGT). All the space groups remain the same Fm3m as that of Yb:CaF2-SrF2. The lattice parameter a, unit cell volume V, as well as bond length of Ca/Sr–F and F–F increase in the sequence of rare-earth ions radius Y3+

We report a diode-pumped passively mode-locked Tm:Sc

Objective This study was aimed to delineate the clinical, 3-dimentional radiographic characteristics and complications of maxillary molar in a non-agomphiasis periodontitis population. Materials and methods Medical records and CBCT images were utilized to identify adult patients with periodontitis in a tertiary referral dental hospital between June 2019 and December 2020. CBCT scan coupled with 3-dimentional reconstruction were used to characterize the detailed bone thickness, absorbing height and position of maxillary molar as well as their associated conditions. All relevant descriptive epidemiological data, clinical information, radiographic details and associated complications were recorded and statistically analyzed. Results According to the above criteria, 577 eligible periodontitis patients were enrolled and defined as research cohort here with mean age 45 ± 4.8 years. Male patients outnumbered females with a gender ratio of 1.23:1. Our results demonstrated that the bone loss of maxillary first molar was more serious than that of second molar with tooth position symmetry. The occurrence of various complications (periodontal abscess, pulp lesions, furcation lesion and mucosal thickening) was significantly correlated to periodontal-related clinical parameters of maxillary molar. Conclusions Our results demonstrated the more serious bone loss of maxillary first molar with tooth position symmetry. The occurrence of various complications was significantly correlated to periodontal-related clinical parameters. Our findings offer valuable information concerning the clinical, radiographic characteristics and complications of maxillary molar in a non-agomphiasis periodontitis population. Clinical relevance: These findings are beneficial for clinicians to comprehensively understand the bone status, pathogenesis, and clinical management of maxillary molar in periodontitis.

This study was aimed to delineate the clinical, CBCT radiographic characteristics, and complications of maxillary molar in a periodontitis population.Medical records and CBCT images were utilized to identify adult patients with periodontitis in a tertiary referral dental hospital between June 2019 and December 2020. CBCT scan images were used to characterize the detailed bone thickness, absorbing height, and position of maxillary molar as well as their associated conditions. All relevant descriptive epidemiological data, clinical information, radiographic details, and associated complications were recorded and statistically analyzed.According to the above criteria, 577 eligible periodontitis patients were enrolled and defined as research cohort here with mean age 45 ± 4.8 years. Male patients outnumbered females with a gender ratio of 1.23:1. Our results demonstrated that the bone loss of maxillary first molar was more serious than that of second molar with tooth position symmetry. The occurrence of various complications (periodontal abscess, pulp lesions, furcation lesion, and mucosal thickening) was significantly correlated to periodontal-related clinical parameters of maxillary molar.Our results demonstrated the more serious bone loss of maxillary first molar with tooth position symmetry. The occurrence of various complications was significantly correlated to periodontal-related clinical parameters. Our findings offer valuable information concerning the clinical, radiographic characteristics, and complications of maxillary molar in a periodontitis population.These findings are beneficial for clinicians to comprehensively understand the bone status, pathogenesis, and clinical management of maxillary molar in periodontitis.

In this Letter, using a Yb,Gd:CaSrF

We report on sub-40 fs pulse generation from a Yb:Sc2SiO5 laser pumped by a spatially single-mode fiber-coupled laser diode at 976 nm. A maximum output power of 545 mW was obtained at 1062.6 nm in the continuous-wave regime, corresponding to a slope efficiency of 64% and a laser threshold of 143 mW. A continuous wavelength tuning across 80 nm (1030 -1110 nm) was also achieved. Implementing a SESAM for starting and stabilizing the mode-locked operation, the Yb:Sc2SiO5 laser delivered soliton pulses as short as 38 fs at 1069.5 nm with an average output power of 76 mW at a pulse repetition rate of ∼79.8 MHz. The maximum output power was scaled to 216 mW for slightly longer pulses of 42 fs, which corresponded to a peak power of 56.6 kW and an optical efficiency of 22.7%. To the best of our knowledge, these results represent the shortest pulses ever achieved with any Yb3+-doped rare-earth oxyorthosilicate crystal.

Purpose: To determine the efficacy of resveratrol in mitigating necrotizing enterocolitis (NEC) in neonatal rats.Methods: Necrotizing enterocolitis (NEC) was induced in neonatal rats using hypoxia and hypothermia. At the completion of treatment, the intestinal tissues of the rats were isolated for evaluation of various biochemical parameters.Results: There was significant increase in the levels of proinflammatory cytokines (TNF-α, IL-6 and IL-1β) and oxidative stress markers (MDA, xanthine oxidase and nitric oxide) in intestinal tissues of NEC rats (p < 0.05). However, resveratrol treatment led to significant decrease in the levels of cytokines and oxidative stress parameters, relative to the NEC group (p < 0.05). Furthermore, Western blotting resultsshowed up-regulation in protein expressions of inflammatory cytokines in NEC rats. However, the protein expressions of inflammatory cytokines were down-regulated in the NEC rats on treatment with resveratrol. Moreover, resveratrol reversed the NEC-induced up-regulations of Bax and caspase-3, as well as NEC-mediated down-regulation of Bcl-2.Conclusion: These results demonstrate that resveratrol mitigates NEC-induced intestinal damage in neonatal rats via anti-inflammatory, anti-apoptotic and antioxidant mechanisms of action. Therefore, resveratrol is a potential therapeutic agent for NEC.

Both tunable and passively mode-locked laser oscillators based on an efficient Yb,Gd:SrF2 crystal are reported for the first time. Charge compensation ions of Gd3+ enhanced the emission and absorption cross section of Yb,Gd:SrF2 crystal markedly. With the aid of birefringent filter, a 61.1-nm continuous-wavelength-tunable laser from 1020.2 to 1081.3 nm was obtained, making it a potential candidate for ultrafast lasers. Based on a semiconductor saturable absorber mirror, a diode-pumped passively mode-locked laser with the pulse width of 951 fs was realized. The oscillator operated at a repetition rate of 92 MHz.

The polarized fluorescence spectra of the Nd:ScYSiO5 (Nd:SYSO) crystal were explored to manifest the tunable single- and multi-wavelength oscillations on the 4F3/2→4I13/2 transitions. A maximum continue-wave output power of 1.26 W was finally obtained from linear cavity. A birefringent filter (BF) was inserted into the V-cavity to achieve wavelength-tuning centered at 1346 nm, 1358 nm, and 1394 nm with tunable range of 4 nm, 6 nm, and 9 nm, respectively. Additionally, simultaneous multi-wavelength oscillation was obtained with the output power in the order of several hundred milliwatt.

Yb,Nd:Sc2SiO5 crystal was investigated by co-doping Nd3+ ions into Yb:Sc2SiO5 crystal. The emission cross section was systematically enquired under different excitation wavelengths at 808, 915, and 980 nm. The emission cross section was enhanced by 18.9% at an excitation wavelength of 980 nm due to energy transfer between Nd3+ ions and Yb3+ ions when comparing with Yb:Sc2SiO5 crystal. The continuous-wave tunable Yb,Nd:Sc2SiO5 laser ranging over 58 nm was achieved from 1030.4 to 1088.4 nm. Mode-locking Yb,Nd:Sc2SiO5 femtosecond laser was obtained with output power of 240 mW, pulse duration of 367 fs, and peak power of 11.5 kW.

In this paper, we have demonstrated an efficient intra-cavity pumped Ho:SSO laser based on a cascaded in-band pumping scheme for the first time. The laser diode at 1.6 µm was used to pump the Tm:YAG crystal. At an incident LD pump power of 18.7 W, dual end-pumped Tm:YAG laser provides the maximum output power of 9.7 W with a slope efficiency of 55.9%. With the same incident LD power, a maximum output power of 4.9 W at 2116.5 nm was achieved with a slope efficiency of 31.6% in the Ho:SSO laser intra-cavity pumped by a Tm:YAG laser. The beam quality factor of the Ho:SSO laser at maximum output level was measured to be 1.1 and 1.2 in the horizontal and vertical directions, respectively.

A kind of saturable absorber (SA) based on layered MoSe2 nanosheets has been fabricated successfully by an ultrasound-assisted liquid phase exfoliation method. The as-prepared MoSe2 SA was characterized and employed as Q-switch in a diode-pumped Tm-doped crystalline all-solid-state laser at around 2 μ m. A stable passively Q-switched 2 μ m laser with a maximum pulse repetition rate of 158 kHz and a minimum pulse width of 520 ns was successfully realized. A maximum average output power of 1.19 W, corresponding to a maximum pulse energy of 12.7 μ J and pulse peak power of 21.8 W, has been obtained. It was the first demonstration of MoSe2 SA in realizing a solid-state 2 μ m pulsed laser, to the best of our knowledge. The results confirmed the excellent ability and promising potential of MoSe2 SA as an optical modulator in generating high repetition rate and short pulsed laser at the midinfrared spectral band.

By transferring the colloidal suspensions of ferroferric-oxide (Fe3O4) nanoparticles (FONPs) onto a quartz plate, zero-dimension FONPs saturable absorber (SA) is successfully fabricated and employed in a Tm:Lu3Al5O12 (Tm:LuAG) bulk laser. The properties of the FONPs-SA including Raman response, nonlinear optical response, and broad-band spectral absorption from 1800 nm to 2500 nm are measured. With the as-prepared FONPs-SA, laser pulses with the shortest duration of 600 ns, a maximum repetition rate of 96 kHz and maximum pulse energy of $4.9~\mu \text{J}$ are obtained, corresponding to a maximum peak power of 8.2 W. This is the first experimental demonstration of the zero-dimension FONPs-SA as Q-switch in $2~\mu \text{m}$ spectral region and even longer wavelength mid-infrared spectral region, to the best of our knowledge, which indicates that the zero-dimension FONPs-SA can act as a promising optical modulator in mid-infrared spectral region.

Tm-doped (Sc0.5Y0.5)2SiO5 (SYSO) crystals were grown by Czochralski method. The UV-VIR-NIR absorption spectra and the near-infrared emission spectra were measured and analysed by the Judd-Ofelt approach. Temperature influence on both absorption and emission spectra has been determined from the data recorded at room temperature and 10 K. It has been found that the structural disorder resulting from dissimilar ionic radii of Sc3+ and Y3+ in the solid solution (Sc0.5Y0.5)2SiO5 crystal brings about a strong inhomogeneous broadening of Tm3+ ions spectra. However, it affects the excited state relaxation dynamics inherent to thulium-doped Y2SiO5 and Sc2SiO5 hosts weakly.

We reported a compact, high-peak-power Nd:ScYSiO5 (Nd:SYSO) laser at 1355 nm pumped by a pulsed laser diode (LD). At free running operation, a maximum output energy of 4.42 mJ was obtained with a repetition rate of 154 Hz, corresponding to an optical-to-optical efficiency of 14.7% and a slope efficiency of 17.9%. Employing V3+:YAG as a saturable absorber, a high-energy and high-peak-power 1355 nm Nd:SYSO laser was achieved. The largest output energy of pulse envelope reached as high as 1.64 mJ. The single pulse energy was up to 273 μJ with a shortest pulse width of 7 ns and a maximum peak power of 39 kW.

Spectroscopic features and laser performance of a novel thulium-doped scandium yttrium silicate crystal Tm 3+ :ScYSiO 5 (Tm:SYSO) are presented. The experimental lifetime of luminescence related to the 3 F 4 – 3 H 6 laser transition of Tm 3+ amounts to 1.1 ms, which is smaller by a factor of three than the calculated radiative lifetime value due to the contribution of nonradiative relaxation. As a consequence of the internal disordered structure of the SYSO host crystal, the luminescence bands of 3 F 4 – 3 H 6 and 3 H 4 - 3 H 6 show significant inhomogeneous spectral broadening as compared with that of SSO. The laser performances were evaluated in an end-pumped cavity using a CW semiconductor laser as a pump source. In a free run regime, the Tm:SYSO laser delivered a maximum output power of 580 mW at 2022 nm, corresponding to a slope efficiency of 17.4%. With a birefringent quartz plate inserted into laser cavity, the laser output wavelength was continuously tuned from 1950 nm to 2057 nm and dual wavelength operations at 2011 nm and 2020 nm, 1987 nm and 2045 nm, 2022 nm and 2044 nm were observed.

The Distributed Face Cooling (DFC) chip was fabricated from four pieces of 1 mm-length Nd:YAG plate sandwiched in four pieces of sapphire heat spreaders through advanced surface activated bonding (SAB) at room temperature. A sub-nanosecond (665.7ps) pulsed DFC-chip tiny integrated laser was achieved with output energy of 21.5 mJ and peak power of 32.3 MW with saturable absorber Cr4+:YAG. By finite element analysis, we confirmed the advantages of heat dissipation from DFC-chip compared with conventional bulk-chip. The SAB-DFC-chip based ubiquitous high peak power tiny integrated laser was experimentally within reach for laser-armed robot.

In this work, we produced Distributed Face Cooling structure, which was made by surface activated bonding technology and allowed to combine transparent heatsink to a gain crystal at room temperature. The sapphire and Nd3+:YAG crystal plates were combined in this fashion to produce 9-crystal chip which was further used to obtain sub-ns, >30W MW peak power laser.

The thermal and spectral properties of a Nd:SrLaAlO4 (Nd:SLA) crystal were systematically studied, including thermal diffusivity, thermal expansion, specific heat, thermal conductivity, polarized absorption and emission spectra. Both continuous-wave (CW) and passively Q-switched Nd:SLA laser operations were investigated. The maximum CW output power of 3.54 W was obtained at 1.077 μm, corresponding to an optical-to-optical efficiency of 46.4%. In the passively Q-switched regime, the maximum average power, pulse repetition rate, and shortest pulse width were 1.8 W, 113 kHz, and 12.6 ns, respectively. All the results indicate that the Nd:SLA crystal is a highly efficient gain medium for laser applications.

The spectral properties of lightly doped Er:CaF 2 and Er,Pr:CaF 2 single crystals were investigated. Benefited from particular clustering effect, 2.79 μm continuous-wave (CW) laser operation was demonstrated in lightly doped 3 at.% Er:CaF 2 crystal. After co-doping small amount of Pr 3+ , the lifetime gap between Er 3+ : 4 I 11/2 and Er 3+ : 4 I 13/2 was shortened from 7.86 ms to about 1 ms. Moreover, the near-infrared and up-conversion fluorescence were significantly quenched. Thus, the CW laser performance was greatly improved. The slope efficiency was effectively improved from 8.0% to 15.8%.

Tunable laser operations in a disordered crystal, Nd:SrLaAlO4, were experimentally reported. The maximum tuning range of 32 nm from 1063 to 1095 nm was achieved with a birefringent filter (Lyot filter). The maximum output power was 1.66 W at the center wavelength of 1075.5 nm, giving an optical-to-optical efficiency of 30%. The output power over 50% of the tuning range was greater than 0.6 W. The special spectral lines, such as 1073, 1080 and 1083 nm, have a potential application in the field of atom and molecular spectroscopy.

The passive Q-switching characteristics of a diode-pumped Tm,Ho:YAP laser at 2 μm based on a MoS2 saturable absorber (SA) is presented for the first time. Pulses as short as 435 ns under a repetition rate of about 55 kHz were generated at the incident pump power of 8.4 W, corresponding to the pulse peak power up to 11.3 W. This is, to the best of our knowledge, the highest pulse peak power, ever obtained from MoS2 based passively Q-switched 2-μm lasers. The experimental results sufficiently validated the feasibility of MoS 2 as SA for solid-state 2-μm lasers.

The anisotropy of thermal property in an Yb,Nd:Sc 2 SiO 5 crystal is investigated from the temperature of 293 to 573 K. Based on the systematical study of thermal expansion, thermal diffusivity, and specific heat, the thermal conductivity in Yb,Nd:Sc 2 SiO 5 crystals orientated at (100), (010), (001), and (406) is calculated to be 3.46, 2.60, 3.35, and 3.68 W/(m·K), respectively. The laser output anisotropy of a continuous-wave (CW) and tunable laser is characterized, accordingly. A maximum output power of 6.09 W is achieved in the Yb,Nd:Sc 2 SiO 5 crystal with (010) direction, corresponding to a slope efficiency of 48.56%. The tuning wavelength range in the Yb,Nd:Sc 2 SiO 5 crystal orientated at (100), (010), and (001) is 68, 67, and 65 nm, separately. The effects of thermal properties on CW laser performance are discussed.

In this paper, we demonstrate a new 2.1-µm Ho:(Sc

In this paper, we demonstrated a linewidth-narrowed continuous-wave (CW) and acousto-optical Q-switched Ho:CaF

In this work we perform a high-resolution spectroscopic investigation of Eu3+-Ce3+ and Pr3+-Ce3+ codoped Y2SiO5 crystals. Satellite line spectra were recorded at low temperatures around the Eu3+:F-7(0) -> D-5(0) and the Pr3+:H-3(4) -> D-1(2) transitions. It is observed that the incorporation of Ce3+ as a codopant notably changes the Eu3+ and Pr3+ satellite line patterns. Satellite lines measured in singly doped Eu3+:Y2SiO5 were found at the same spectral positions in Eu3+-Ce3+ codoped crystals. These coincident lines were concluded to be due to pairs of Eu3+ ions. Extra satellite lines appeared in the codoped crystals, which were assigned to Ce3+ related structures such as Ce3+-Eu3+ pairs. The analysis of the Pr3+ satellite line spectra presents further challenges. Satellite lines associated to Pr3+ pairs show weaker intensity, presumably due to the efficient quenching of the Pr3+ D-1(2) emission through cross-relaxation paths (D-1(2) -> (1)G(4); H-3(4) -> F-3(4)). The investigation of the Eu3+ and Pr3+ satellite line patterns in Y2SiO5 is particularly interesting for their exploitation in rare-earth based quantum computation schemes. (C) 2015 Elsevier B.V. All rights reserved. (Less)

In this Letter, we demonstrate the anisotropy of laser emission in disordered Nd:ScYSiO5 (Nd:SYSO) crystals cut along the optical indicatrix axes. High-powered lasers with different oscillation wavelengths and polarizations are realized by using different oriented crystals as gain media. For Y-cut crystals, the dual-wavelength laser vibration direction is found to be along the X axis and a maximum output power of 9.43 W is obtained, giving an optical-to-optical conversion efficiency of 48.8% and a slope efficiency of 51.3%. For X- and Z-cut crystals, 1075 and 1078 nm lasers operating orthogonally polarize oscillate with total output powers of 7.07 and 8.43 W, respectively. The experimental results reveal that the intrinsic anisotropy for the monoclinic disordered laser crystals could make laser design flexible and controllable.

A continuous wave (CW) tunable laser based on an alloyed oxyorthosilicate Yb:(Gd0.1Y0.9)2SiO5 was demonstrated for the first time. With an output coupler (OC) of T = 10%, a maximum output power of 958 mW was obtained with a slope efficiency of 18.2%. Simultaneous multi-wavelength operation was also observed with an OC of T = 4%. The M2 factor of the CW laser beam was measured to be 1.06. The thermo-optic coefficient was estimated to be 7.1 × 10−6/K. By using a 400 μm-thick GaAs wafer as saturable absorber, a stably Q-switched laser at 1080.4 nm was also firstly realized. A minimum pulse duration of 60.2 ns was obtained with a repetition rate of 47.6 kHz under an absorbed pump power of 11.25 W. The corresponding highest pulse energy and peak power were 5.3 μJ and 88 W, respectively. By using a V-type cavity and an OC of T = 4%, the laser can be tuned in the range from 1021 to 1094 nm.

Based on a graphene oxide absorber mirror, the laser-diode pumped mode-locked Yb:Y2SiO5 (Yb:YSO) laser was demonstrated for the first time. The laser generated pulses with pulse duration as short as similar to 763 fs and average output power of 700 mW at the central wavelength of 1059 nm. The corresponding peak power and energy of a single pulse were similar to 8.6 kW and similar to 7.4 nJ, respectively. To our best knowledge, this is the shortest bulk mode-locked laser based on graphene oxide. (C) 2014 Elsevier Ltd. All rights reserved.

We report on a Kerr-lens mode-locked Yb:YSO lasers for the first time. Pumped by a single-mode fiber laser with high brightness and linear polarization, the Yb:YSO laser can deliver as high as 2 W average power with as short as 95 fs pulse duration at the repetition rate of 137.2 MHz, resulting in the single pulse energy of 14.8 nJ and the peak power of 155.7 kW. This work proves the potential on generation of sub-100 fs pulses with multi-watt level average power with the Yb doped oxyorthosilicates crystals.

A sub-nanosecond (666 ps) Distributed Face Cooling (DFC) handheld laser has been demonstrated with pulse energy of 21 mJ, depolarization ratio of 1.56% and brightness of 20 TWcm−2sr−1 at 10Hz.

We demonstrated, for the first time to our knowledge, a diode-pumped Kerr-lens mode-locked (KLM) Yb:Y2SiO5 laser. No cavity dispersion compensation components were applied and the shortest pulse width of 1.2 ps was obtained. The maximum KLM output power of 1.05 W was obtained at a central wavelength of 1,058 nm. The pulse repetition rate was 97.8 MHz, corresponding to a pulse energy of 10.7 nJ and a peak power of 8.9 kW, respectively.

Efficient diode-pumped Tm:LuAG lasers operating in continuous wave, dual-wavelength,and passive $Q$ -switching regimes have been demonstrated. A maximum output power of 4.42 W with a beam quality of $\mathrm{M}^{\mathbf {2}}\le 1.45$ at 2021.2 nm was obtained, corresponding to a slope efficiency of 49.5%. Using a birefringent quartz plate, the Tm:LuAG laser emitted the highest output power of 2.3 W at dual-wavelength of 2022 and 2030 nm. With a SWCNT-SA employed as saturable absorber, passively $Q$ -switched Tm:LuAG laser was realized, which generated the shortest pulses of 405 ns at 2021.6 nm and a maximum single pulse energy of $40.6~\mu $ J at 2019.7 nm.

High-quality monolayer graphene was successfully fabricated by chemical vapor deposition technology. By using the graphene as a saturable absorber, the Yb:Sc 2 SiO 5 crystal passively mode-locked laser was demonstrated for the first time. Stable mode-locked laser pulses were obtained with a repetition rate of 90.7 MHz and an average output power of 480 mW at the center wavelength of 1062.8 nm. The maximum single pulse energy and the maximum peak power were 5.3 nJ and 378 W, respectively.

We demonstrate a diode-pumped picosecond Yb-doped silicate Yb3+:Sc2SiO5 (Yb:SSO) chirped pulse amplifier. The seed source with a pulse width of 220 fs is a diode-pumped Yb:KGW femtosecond oscillator. A single chirped volume Bragg grating is employed both as a pulse stretcher and as a compressor to improve the compactness of the system. Stretched pulse is amplified using a diode-pumped Yb:SSO regenerative amplifier. The maximum amplified pulse energy obtained at a pump power of 13.5 W is 450 µJ. The amplified pulse is centered at 1033.3 nm before compression at a frequency of 1 kHz. After compression, the pulse energy is 315 µJ with a pulse duration of approximately 1 ps.

In this work, we have compared the performance of single rod crystal to a newly developed Distributed Face Cooling (DFC) structure which was made by surface activated bonding technology and allowed to combine transparent heatsink to a gain crystal at room temperature. The Sapphire and Nd3+:YAG crystal plates were combined in this fashion to produce nine crystal chip which was further used to obtain CW output. Slope efficiencies obtained in this experiment were 27% and 64% for single rod and DFC structure, respectively. This is the first demonstration of distributed face cooling system outperformed conventionally single rod system.

In this work the performance of two yttrium calcium oxyborate (YCOB) crystals made by Czochralski and Bridgman growth process was measured. By using high peak power, passively Q-switched Nd3+:YAG/Cr4+:YAG microlaser, high conversion second harmonic generation efficiency were obtained. Laser pulses at 532 nm with 1.14 mJ energy and 223 ps duration were obtained with a 15-mm long YCOB crystal that was grown by Bridgman method. The conversion efficiency was 70.2%, comparable with the conversion efficiency of 72.8% that was achieved with 10-mm long lithium triborate (LBO) nonlinear crystal. Also, for the first time, experimental data on temperature tuning in type I YCOB crystal was measured with linear slope in 200°C temperature range equal to -0.057%/°C and -0.064%/°C for the Czochralski and Bridgman grown crystals, respectively. Such YCOB nonlinear crystal can become a serious option for developing laser sources with high-peak power at high repetition rate that can operate in harsh environment.

A diode-pumped passively Q-switched Tm 3+ :Sc 2 SiO 5 laser with a single-walled carbon nanotube saturable absorber is demonstrated for the first time. The maximum average output power of 189 mW has been achieved at 1970 nm under an absorbed pump power of 4 W. The minimum pulse width of 442 ns was obtained at a repetition rate of 55.6 kHz, corresponding to the highest peak power of 7.7 W and single pulse energy of 3.4 μJ, respectively.

We experimentally investigate the continuous-wave (cw) and acousto-optical (AO) Q-switched performance of a diode-pumped Ho:(Sc0.5Y0.5)2SiO5 (Ho:SYSO) laser. A fiber-coupled laser diode at 1.91 μm is employed as the pump source. The cw Ho:SYSO laser produces 13.0 W output power at 2097.9 nm and 56.0% slope efficiency with respect to the absorbed pump power. In the AO Q-switched regime, at a pulse repetition frequency of 5 kHz, the Ho:SYSO laser yields 2.1 mJ pulse energy and 21 ns pulse width, resulting in a calculated peak power of 100 kW. In addition, at the maximum output level, the beam quality factor of the Q-switched Ho:SYSO laser is measured to be about 1.6.

In this paper, we demonstrate the continuous-wave and acousto-optical Q-switched performance of diode-pumped slab Ho:(Sc0.5Y0.5)2SiO5 (Ho:SYSO) laser at 2.1 µm for the first time. Two 1.91-µm laser diodes were used to pump the Ho:SYSO crystal. With a wing-pumping structure, at absorbed pump power of 44.7 W, the continuous wave slab Ho:SYSO laser produced 20.7 W maximum output power at 2097.9 nm, resulting in a slope efficiency of 53.1% with respect to the absorbed pump power. In the Q-switched regime, the slab Ho:SYSO laser produced up to 3.4 mJ pulse energy with 20 ns minimum pulse width at pulse repetition frequency of 5 kHz, corresponding to a peak power of 170 kW.

A diode-end-pumped passively Q-switched ytterbium-doped yttrium aluminum garnet (Yb:YAG) laser with gallium arsenide (GaAs) wafer as saturable absorber has been realized. In the experiment, two pieces of GaAs wafers with respective thicknesses of 400 and 700 μm were used respectively. The output laser characteristics such as the pulse duration, single pulse energy and peak power, have been measured. By using thicker GaAs wafer as saturable absorber, a minimum pulse duration of 3.5 ns was obtained with an average output power of 361 mW and a pulse repetition rate (PRR) of 25 kHz, corresponding to a single pulse energy of 19.6 μJ and a peak power of 5.7 kW. With a 400 μm-thick GaAs wafer as saturable absorber, a maximum output power of 469 mW was achieved. The central wavelength of the laser was measured to be 1050.4 nm at pump power of 7.8 W and dual wavelength operation peaked at 1049.3 nm and 1051.6 nm was observed at a high pump power of 10 W. By considering Gaussian spatial distribution and the thermal effects in the gain medium, the coupled rate equations for passively Q-switched Yb:YAG laser with GaAs saturable absorber were given.

Praseodymium and cerium co-doped yttrium silicate (Pr,Ce:YSO) crystal with high optical quality was grown by the Czochralski method. The segregation coefficient of Pr3+ and Ce3+ is measured to be 0.547 and 0.136, respectively. The polarized absorption bands centered at 268 nm, 299 nm and 356 nm were assigned to 4f (2F5/2)→5d inter-configuration transitions of Ce3+, while bands centered at 220 nm and 250 nm were assigned to 4fn–4fn−15d transitions of Pr3+. The VUV–UV excitation spectra for monitoring Pr3+ emissions centered at 610 nm (1D2→3H4) and 489 nm (3P0→3H4), as well as Ce3+ emission centered at 450 nm were recorded at T=8 K in the range of 100 nm–320 nm. Polarized excitation spectra for Ce3+ emission centered at 424 nm and Pr3+ emission centered at 611 nm were recorded at T=300 K. Polarized emission spectra were obtained upon excitation at 365 nm and 456 nm at T=300 K. Lifetimes were estimated to be 170 μs for Pr3+ (1D2), 3 μs for Pr3+ (3P0) and 39 ns for Ce3+ (5d1).

Efficient laser emission at 2 μm is demonstrated from Tm:Sc2SiO5 crystal under end-pumping with a continuous wave (cw) diode laser at 790 nm. A maximum output power of 1.02 W is obtained for the incident pump power of 6.78 W, corresponding to an optical-to-optical efficiency with respect to the incident pump power of 14.7%. At this output level the spectrum of emission was centered at 1976 nm with a broad bandwidth of 28 nm. The laser slope efficiency with respect to the incident pump power was 16.1%. Influence of the output mirror transmittance or of the Tm:Sc2SiO5 crystal temperature on the laser output performance is investigated.

We report on the sub-100 fs pulse generation in a diode pumped Yb 3+ :Sc 2 SiO 5 (Yb:SSO) laser. Pumped by a 976 nm single emitter diode and mode-locked with a SESAM, the laser generated stable mode locked pulses with 71 fs duration, 89 MHz repetition rate, and an average power of 38 mW at 1044.6 nm under the incident pump power of 6.5 W. To the best of our knowledge, this is the shortest pulse ever produced from an Yb 3+ doped orthosilicate crystal laser.

In this work, we have compared the Q-switched performance of single rod crystal to a newly developed distributed face cooling structure. This structure was made by surface activated bonding technology and allowed to combine transparent heatsink to a gain crystal at room temperature. The Sapphire and Nd3+:YAG crystal plates were combined in this fashion to produce eight crystal chip which was further used to obtain Q-switch pulses with Cr4+:YAG crystal as saturable absorber. Energy of 9 mJ and pulse duration of 815 ps were achieved. Although the energy obtained with single rod system was 10 mJ, the degradation of the beam prevents such crystal to be used in further applications. This is the first demonstration of distributed face cooling system outperformed conventionally single rod system.