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The rational control of intrinsic defects in materials can significantly enhance their scientific and technological potentials, but it remains a long‐standing challenge in nanocrystal‐in‐glass composites (NGCs). Herein, a defect engineering strategy mediated by the mixed alkali effect is proposed and experimentally demonstrated for NGCs. Interestingly, the hybridization of large alkali ions can effectively increase the barrier of Li+ migration and reduce the Li‐related defects in LiNbO3 NGC. As a result, a novel LiNbO3 NGC with greatly reduced Li‐related defects, high crystallinity of over 60%, and excellent optical transmission are successfully fabricated. This unique NGC configuration facilitates efficient transverse second harmonic generation (TSHG) in a broad wavelength region. Based on the above effects, a standard TSHG device is fabricated and implemented to monitor ultrashort optical pulses with duration in the order of ≈10−13 s over a broad wavelength region, down to 780 nm. The proposed strategy not only provides a new idea for defect engineering in materials science but also has great significance for boosting the practical applications of NGCs in ultrashort optical pulse monitoring. [ABSTRACT FROM AUTHOR]

Effective online monitoring of the spatial distribution of high‐energy radiation is of significant importance in various fields such as medical imaging, high‐energy physics, and homeland security. However, achieving radiation detectors with both high sensitivity and minimal disturbance is an enormous challenge. The present study introduces a solution to this bottleneck issue through the development of a full‐inorganic scintillating fiber, successfully demonstrating its application in constructing a radiation monitoring device. The scintillating fiber, activated with Ce3+ and fabricated using the melt‐in‐tube approach, is lightweight with a density of 2.5 g cm−3 and exhibits efficient scintillating emission with a light yield of 4000 photons MeV−1. These characteristics enable the achievement of radiation detection with high sensitivity while keeping disturbance to the incident radiation beam at a minimum. Furthermore, 2D and 3D radiation beam monitors are constructed based on these scintillating fibers, facilitating spatial radiation monitoring. The findings demonstrate that full‐inorganic scintillating fibers and devices offer a synergistic combination of high sensitivity and negligible disturbances. This progress not only introduces a novel full‐inorganic fiber for radiation detection but also suggests promising applications in various nuclear fields where 3D radiation beam tracking is essential. [ABSTRACT FROM AUTHOR]

Oxyfluoride transparent glass‐ceramics (GC) are widely used as the matrix for rare‐earth (RE) ions due to their unique properties such as low phonon energy, high transmittance, and high solubility for RE ions. Tb3+ doped oxyfluoride glasses exhibit a large absorption cross section for ultraviolet (UV) excitation, high stability, high photoluminescence quantum efficiency, and sensitive spectral conversion characteristics, making them promising candidate materials for use as the spectral converter in UV photodetectors. Herein, a Tb3+ doped oxyfluoride GC is developed by using the melt‐quenching method, and the microstructure and optical properties of the GC sample are carefully investigated. By combining with a Si‐based photo‐resistor,a solar‐blind UV detector is fabricated, which exhibits a significant photoelectric response with a broad detection range from 188 to 400 nm. The results indicate that the designed UV photodetector is of great significance for the development of solar‐blind UV detectors. [ABSTRACT FROM AUTHOR]

Glass ceramics may exhibit enhanced functionalities compared to the glass and crystal counterparts due to the synergistic effect with the "1+1 > 2" feature in a cooperative manner. Nonlinear optical property is expected to be next breakthrough in presenting synergistic effect in glass ceramics. In this article, we give a comprehensive review of the recent progress of the development in nonlinear glass ceramics with unique photonic domain structure, emphasizing their synergistic effect in nonlinear response. The applications in photonics of the nonlinear glass ceramics are also described. Finally, we also present the opportunities and challenges for further exploring synergistic effect in nonlinear response in glass ceramics. [ABSTRACT FROM AUTHOR]

CsPbI3 perovskite quantum dots (QDs) doped borosilicate glass was prepared by the process of melt‐quenching and subsequent annealing. With the introduction of ZnO to the parent glass as the glass network intermediate, the optical properties of the resultant samples are dramatically enhanced. Both the photoluminescence (PL) intensity and photoluminescence quantum yield (PLQY) shows a strong dependence on ZnO concentration as ZnO is found to facilitate the precipitated of the QDs by reducing the connectivity of three‐dimensional glass network built from SiO4 tetrahedrons. The tunable visible‐band PL emission of the CsPbI3 QD‐doped glass could find potential applications in white LEDs and lasers. [ABSTRACT FROM AUTHOR]

The wide applications of ionizing radiation in various important technologies such as 3D industrial tomography, mammography, and small‐animal micro‐CT with low energy X‐ray have increased the demand for precise radiation measurement. Detection technologies have undergone remarkable progress, but most of them strictly rely on the complicate calibration process, thus remarkably limiting their applications. Here, a nanostructured glass composite system for self‐calibrated radiation dose rate detection (at 40 keV X‐ray) is described. Results show that the in situ precipitation of LiGa5O8 nano‐domains from glass composite results in unique emission centers at ≈496 and ≈718 nm with distinct ionizing radiation response. Subsequently, the radiation level is directly assessed by comparing the radiative transition ratio of these two centers. The nanostructured glass composite can also be constructed into fiber, which exhibits perfect core‐clad configuration and maintains excellent optical activity. The novel principle device with self‐calibrated function is successfully constructed, and the application for online radiation monitoring is demonstrated. The results not only provide an alternative opportunity for developing the next generation of ionizing radiation detection system, but also suggest a powerful pathway for the creation of new optical function through nanocrystallization of glass. [ABSTRACT FROM AUTHOR]

Gradient functionalization is a widely applied process in materials science that involves generating gradient distribution of composition or structure to yield materials with new functions or improved properties. Here an interfacial engineering is described for construction of gradient fiber, which exhibits gradient distribution of active centers, bonding configuration, and the resultant optical response. It is shown that the interfacial diffusion of protype niobium (Nb) in the core and cladding region of the fiber can be tuned via rational control of the viscosity of melt and the subsequent thermal activation. This leads to gradient distribution of Nb species and active [NbO6]7− centers within 10–20 µm region. As a result, unique optical properties including the tunable energy transfer between active centers and special annular emission beam can be obtained. These results highlight a fundamental principle to develop novel photonic fibers and provide a great step in expanding the scope of gradient materials. [ABSTRACT FROM AUTHOR]

Phase-matched second-harmonic generation (SHG) in azodye-doped polymethylmethacrylate films was demonstrated using the nonresonant optical poling technique. During the seeding process, samples were irradiated simultaneously by coherent superposition of the fundamental and the second-harmonic light of a femtosecond laser. Optical poling experiments were performed at three wavelengths of 1500, 1320, and 1300 nm, respectively. The quadratic dependence of SHG on the film thickness showed that a χ[sup (2)] grating that satisfied the phase-matching condition for SHG was optically induced in the polymer films. The SHG conversion efficiency of a 105 μm thick film was estimated to be about 2%. A relaxation retardation effect of the photoinduced χ[sup (2)] was also observed in the thick films. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Abstract: Borosilicate glasses doped with PbSe quantum dots (QDs) were prepared by a conventional melt‐quenching process followed by heat treatment, which exhibit good thermal, chemical, and mechanical stabilities, and are amenable to fiber‐drawing. A broad near infrared (NIR) photoluminescence (PL) emission (1070‐1330 nm) band with large full‐width at half‐maximum (FWHM) values (189‐266 nm) and notable Stokes shift (100‐210 nm) was observed, which depended on the B2O3 concentration. The PL lifetime was about 1.42‐2.44 μs, and it showed a clear decrease with increasing the QDs size. The planar [BO3] triangle units forming the two‐dimensional (2D) glass network structure clearly increased with increasing B2O3 concentration, which could accelerate the movement of Pb2+ and Se2− ions and facilitate the growth of PbSe QDs. The tunable broadband NIR PL emission of the PbSe QD‐doped borosilicate glass may find potential application in ultra‐wideband fiber amplifiers. [ABSTRACT FROM AUTHOR]

We fabricated a series of stable Er-doped CaO-Al2O3(Ga2O3) glasses by aerodynamic levitation (ADL) method. Using thermal analysis, we studied the influence of composition on the thermal stability of the glasses. The results unraveled the significance of composition on the stability of glasses. Magic angle spinning nuclear magnetic resonance (MAS-NMR) and Raman spectra were used to analyze the glass microstructure. The optical and spectroscopic properties were examined by UV-Vis absorption, steady-state fluorescence spectroscopy, transient state fluorescence spectroscopy, and luminescence quantum yield measurements. The results unraveled a clear concentration-dependent up-conversion and NIR emissions of Er3+, with obvious spectral broadening and redshift. The related mechanisms of decrease in fluorescent lifetime (from about 9 ms to 2 ms) and quantum yield (from about 75% to 5%) are discussed. [ABSTRACT FROM AUTHOR]

The development of doped photonic glass is of fundamental importance for various applications, including telecommunication, lasers, and photovoltaics. Despite the great advances in doping techniques, a long-standing barrier remains concerning how to gain better control over the properties of active dopants in disordered systems. Here, we provide a brief overview of recent progress on the engineering of the chemical environment and chemical state of dopants in glass by tuning the topological features, including sublattices and packing manner of the network. The methods allow us to finely tune the chemical state of active dopants over a wide range of length scales, from dispersed ions to aggregated clusters to nanoparticles, and also offer new opportunities to engineer the local crystal field around active dopants. This inherent structure-based strategy leads to intriguing optical phenomena such as tunable luminescence and notable enhancements in radiative transition probability. [ABSTRACT FROM PUBLISHER]

ABSTRACT Red-emitting Mg4Nb2O9:Eu3+ phosphor is synthesized via a solid-state reaction method in air, and its crystal structure and luminescence are investigated. The phosphor can be excited efficiently by ~ 395 nm light, coupled well with a ~ 395 nm near-ultraviolet chip and emits red light at ~ 613 nm with sharp spectra due to 5 D0 → 7 F2 transition of the Eu3+ ion. Mg4Nb2O9:Eu3+ phosphor sintered at 1350 ºC shows Commission international de I'Eclairage (CIE) chromaticity coordinates of x = 0.6354, y = 0.3592, and is a potential red-emitting phosphor candidate for white light-emitting diodes (W-LEDs) under ~ 395 nm near-ultraviolet LED chip excitation. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Cr3+-doped LiInSiO4 phosphors were prepared by a solid-state reaction method. X-ray diffraction measurement was carried out for crystalline phase identification. Absorption, photoluminescence, excitation, and time-resolved spectra were measured to investigate the optical properties of the phosphors. Two broadband near-infrared emissions centered at 920 and 1172 nm were observed. Time-resolved spectra show that the emission at 1172 nm decays more quickly than the emission at 920 nm. The electron spin resonance spectra exhibit a broad resonance signal at g = 1.96 because of exchange-coupled Cr3+ pairs. The value of Dq/B for low and intermediate crystal fields was evaluated. We suggest that Cr3+ incorporated into different octahedral sites of the crystal is responsible for the different near-infrared luminescence. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we present the absorption and photoluminescence properties of Pr3+, Sm3+ and Dy3+-doped transparent oxyfluoride alumino-silicate glass ceramics and Sm3+ and Dy3+-doped oxyfluoride germanate glasses. The X-ray diffraction (XRD) and differential thermal analysis (DTA) profiles of these glasses have been carried out, to confirm their structure and thermal stability. These glasses or glass ceramics have shown strong emission and absorption bands in visible and near-infrared (NIR) region. From the measured absorption spectra, Judd–Ofelt (J–O) intensity parameters (Ω 2, Ω 4 and Ω 6) have been calculated for all the studied ions. Compared to Pr3+, Sm3+ and Dy3+ doped glasses, their respective glass ceramics have shown stronger emissions due to LiGdF4 crystalline phase in alumino-silicate glass ceramics. For Pr3+ doped glass and glass ceramic, emission bands centered at 527nm(3P0→3H5), 610nm(3P0→3H6), 640nm(3P0→3F2), 678nm(3P1→3F3), 702nm(3P0→3F3) and 721nm(3P0→3F4) have been observed with 445nm(3H4→3P2) excitation wavelength. Of them, 640nm(3P0→3F2) has shown bright red emission. Emission bands of 4G5/2→6H5/2 (562nm), 4G5/2→6H7/2 (598nm), 4G5/2→6H9/2 (644nm) and 706nm(4G5/2→6H11/2) for the Sm3+: glass and glass ceramic, with excitation at 6H5/2→4F7/2 (402nm) have been recorded. Of them, 4G5/2→6H7/2 (598nm) has shown a bright orange emission. With regard to the Dy3+: glass and glass ceramic, a bright fluorescent yellow emission at 576nm(4F9/2→6H13/2) and blue emission at 485nm(4F9/2→6H15/2) have been observed, apart from 4F9/2→6H11/2 (662nm) emission transition for glass ceramic with an excitation at 388nm(6H15/2→4I13/2+4F7/2) wavelength. For germanate glasses, emission bands of 4G5/2→6H5/2 (564nm), 4G5/2→6H7/2 (601nm), 4G5/2→6H9/2 (644nm) and 705nm(4G5/2→6H11/2) for the Sm3+: glass, with an excitation at 6H5/2→4F7/2 (401nm) have been recorded. Of them, 4G5/2→6H7/2 (601nm) has shown a bright orange emission. With regard to the Dy3+: glass, a bright fluorescent yellow emission at 576nm(4F9/2→6H13/2) and blue emission at 482nm(4F9/2→6H15/2) have been observed, apart from 4F9/2→6H11/2 (661nm) emission transition with an excitation at 386nm(6H15/2→4I13/2+4F7/2) wavelength. The stimulated emission cross-sections of all the emission bands of Pr3+, Sm3+ and Dy3+: glasses and glass ceramics have been computed based on their measured full-width at half maxima (FWHM, Δλ) and measured lifetimes (τm ). [Copyright &y& Elsevier]

Abstract: Broadband infrared luminescence is observed in various Bi-doped oxide glasses prepared by conventional melting-quenching technique. The absorption spectrum of the Bi-doped germanium oxide glass consists of five broad peaks at below 370, 500, 700, 800 and 1000nm. The fluorescence spectrum exhibits a broad peak at about 1300nm with full width at half maximum (FWHM) of more than 300nm when excited by an 808nm laser diode. The fluorescence lifetime at room temperature decreases with increasing Bi2O3 concentration. Influence of the glass composition and melting atmosphere on the fluorescence lifetime and luminescent intensity is investigated. The mechanism of the broadband infrared luminescence is suggested. The product of stimulated emission cross-section and lifetime of the Bi-doped aluminophosphate glass is about 5.0×10−24 cm2 s. The glasses might be promising for applications in broadband optical fiber amplifiers and tunable lasers. [Copyright &y& Elsevier]

Metal halide perovskites (MHPs) have attracted increasing attention in various optoelectronic devices due to their exceptional optical and electrical properties. The high precision patterning of MHPs is crucial adjective for device fabrication, while it is severely hindered by the active and sensitive chemistry of MHPs. In this work, high resolution and tunable nanostructuring of 2D MHP films are achieved by ultrafast laser direct writing (ULDW). The feature size of the created structure is down to 47 nm (λ/21), which is far beyond the diffraction limit of the optical system. The study proves the critical influence of the thermodynamic properties of materials on structure morphologies and establish a new mechanism of molten phase self‐evolution (MPSE) for the formation of super‐solution convex structures, which provides a new understanding for ultrafast laser‐matter interaction and high‐resolution patterning with ULDW. Different structure morphologies bring tunable optical properties. The applications are demonstrated in multimode information storage and encryption. The findings open new approaches to achieve hyperfine multi‐morphological structures on MHPs, which can boost many MHPs integration applications in nanophotonics, on‐chip electronics, and information encryption. [ABSTRACT FROM AUTHOR]

Polymeric g‐C3N4 with controllable photoluminescence emission wavelength in the whole visible light range (450–650 nm) is synthesized through the one‐step molecular doping during the thermal condensation process of g‐C3N4 conjugated framework, which opens up its application beyond the conventional catalysis scopes. By adjusting the doped content of hetero‐molecules, the modified g‐C3N4 with the optical properties controlled according to the demand of practical applications can be facilely and largely obtained. It overcomes the limitation of the narrow adjusting range of conventional g‐C3N4 on optical properties and makes it become more promising for applications in solid‐state displays. The corresponding multiple‐color g‐C3N4‐based LED devices and the white‐light LEDs with high quality can be obtained as supported by experiments and theoretical calculations. Moreover, the effect of doped molecule on the π‐conjugated system of g‐C3N4 is systematically studied here, and the tunable luminescence mechanism is proposed. [ABSTRACT FROM AUTHOR]

All inorganic halide perovskite quantum dots (PQDs) exhibit excellent optical properties and have been intensively exploited for diverse applications in the field of optoelectronics. However, their inherent frangibility remains an enormous challenge for both practical applications and scientific research. The recently emerged oxide glasses doped with such PQDs exhibit high stability against degradation, which is promising for practical applications. Here, borosilicate glasses doped with CsPbBr 3−x I x PQDs were prepared by the traditional melt-quenching and subsequent annealing process. By introducing alkaline metal oxides as the glass network modifier to adjust glass network structure, the optical properties of the precipitated PQDs are significantly enhanced. The photoluminescence (PL) intensity and photoluminescence quantum yield (PLQY) can be enhanced by up to 200 % and 29 % for the sample fabricated under optimal conditions, respectively. By leveraging the strong PL of the developed PQD-doped glasses, we demonstrate the fabrication of phosphor-converted light emitting devices for white light illumination and plant illumination based on samples with PL peak wavelengths at approximately 570 nm and 650 nm, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Luminescences from bismuth-doped lime silicate glasses were investigated. Luminescences centered at about 400, 650, and 1300nm were observed, excited at 280, 532 and 808nm, respectively. These three luminescence bands arise from three different kinds of bismuth ions in the glasses. The visible luminescences centered at 400 and 650nm arise from Bi3+, and Bi2+, respectively. The infrared luminescences cover the wavelength range from 1000 to 1600nm when exited by an 808nm laser diode. The full width at half maximum (FWHM) of the infrared luminescences is more than 205nm. The intensity of the infrared luminescence decreases with the increment in CaO content. We suggest that the infrared luminescences might arise from Bi+. Such broadband luminescences indicate that the glasses may be potential candidate material for broadband fiber amplifiers and tunable lasers. [Copyright &y& Elsevier]

Near infrared to visible up-conversion luminescence in Er 3+ single doped BaCl 2 , BaF 2 and NaYF 4 phosphors were compared. Intense blue emission at 410 nm due to 2 H 9/2 → 4 I 15/2 transition and greenish-blue emission at 496 nm due to 4 F 7/2 → 4 I 15/2 transition were only observed in BaCl 2 :Er 3+ when excited by 808 nm and 976 nm laser diodes, respectively. The phenomena can be ascribed to the direct two-step excitation processes which occur in the chlorides where multiphonon relaxation is rapidly suppressed. In addition, the intensity of upconversion emission in BaCl 2 :Er 3+ is greatly enhanced upon broadband near-infrared excitation. [ABSTRACT FROM AUTHOR]

Abstract: NIR luminescence phosphors Sr2CeO4:Yb3+, M + (M +=Li+, Na+, K+) were synthesized by conventional solid-state method in the present paper. The prepared phosphors are characterized by XRD and fluorescence spectrometer. Under UV light excitation, the NIR emission intensity of Yb3+:2F5/2→2F7/2 around 1μm of Sr2CeO4:Yb3+ is strengthened significantly by introducing appropriate alkali metal cations dopants (Li+, Na+, K+) into the crystalline lattice. The relevant mechanisms have been discussed in detail. The peculiar optical properties make Sr2CeO4:Yb3+, M + (M +=Li+, Na+, K+) promising for potential application in the high efficiency silicon-based solar cells. [Copyright &y& Elsevier]

Highlights: [•] Phosphors are synthesized by solid-state reaction method in air. [•] Phosphors contain SrMgAl10O17 and Al2O3 phases. [•] Emission of phosphor is greatly enhanced due to multiple scattering and absorption of excitation light. [•] White-LED has been demonstrated by blend composition phosphors pumped with a 397nm near UV LED chip. [ABSTRACT FROM AUTHOR]

The ultra-wideband near-infrared (NIR) emission of Bi-doped glass and fiber makes it play an increasingly important role in laser technology and optical communication system. However, challenge remains to grasp the original of NIR emission and manipulate the valence state of bismuth for efficient Bi-doped fiber lasers and amplifiers. In this article, we present a facile method to control the valence of bismuth by using one kind of porous host, the nano-porous silica glass (NPSG). Bi-doped silicate glass with novel NIR emission was obtained in NPSG based on glass phase separation technology (GPST). The valence state and NIR luminescence of bismuth can be controlled by sintering of NPSGs impregnated with Al 3 + and P 5 + ions in inert atmosphere. Three kinds of bismuth active centers (BACs) with their own fluorescence characteristics are formed in NPSG. Al can disperse bismuth active centers (BACs) to enhance O band NIR emission; P can promote the reduction of bismuth in glass to produce up-conversion and S+C+L+U band NIR emission. This work pushes us to take a big step towards understanding the truth of NIR emission of bismuth. The GPST may serve as key technology for efficient Bi-doped fiber lasers and amplifiers. [ABSTRACT FROM AUTHOR]

Abstract: Silver nanoparticles were prepared by a focused femtosecond laser irradiation in a 5mM AgNO3 solution in the presence of TiO2 sol. TEM analysis revealed that the size of silver nanoparticles was less than 20nm. A mechanism for the precipitation of silver nanoparticles was proposed. Nonlinear absorptions and optical limiting properties of silver nanoparticles contained solution were also measured. It is observed that the composite material showed strong self-focused effect and significant optical limiting property. [Copyright &y& Elsevier]

CsPbBr 3 perovskite QDs are precipitated in a borosilicate glass matrix, while protects efficiently the QD from photo-induced and chemical degradation. We show that the CsPbBr 3 QD doped glasses exhibit strong visible photoluminescence (PL), which is dependence on the concentration that can be controlled by heat treatment conditions. Due to the stabilization by the glass matrix, we are able to determine the nonlinear optical (NLO) properties with a Z-scan technique. We observe a cross-over from saturated absorption (SA) to reverse saturated absorption (RSA) by either increase the pumping intensity or the QD size, reminiscent of quantum size effect in the NLO response. The RSA is associated with two-photon absorption (TPA) that induces strong upconversion luminescence of QD doped glass samples. Our results imply that the glasses containing CsPbBr 3 QDs may find potential applications from solid state lighting to ultrafast optical switches. [ABSTRACT FROM AUTHOR]

Transparent glass ceramics (TGCs) with minimized scattering loss offer the combined characteristics of both glasses and (transparent) ceramics. The functionalities of the dispered crystals make TGCs a new generation of tailorable optical materials with a wide range of applications from optics to photonics. Most of conventional glass ceramics (GCs), e.g., silicate glass ceramics, contain crystals involving both network formers and modifiers, and they are known for their superior mechanical/thermal performances. In this paper, we pay more attention to those TGCs containing crystalline phases composed of only network modifiers, including nanocrystals of noble metals, metal fluorides, oxides, chalcogenides, etc. We review recent advances in conventional fabrication methods as well as in emerging techniques for the production of TGCs, such as solid state reaction, sol–gel and laser–induced crystallization. We then discuss the applications of TGCs, particularly the TGCs functionalized by crystals that exhibit various optical functionalities, including photoluminescence, optical nonlinearity, plasmonic absorption, etc. Experimental advances in the use of TGCs for lasers, optical amplifiers and different spectral converters are highlighted. We also anticipate that TGCs will find new applications, and the investigations into TGCs will unravel the mechanism of crystal formation, and hence, lead to the discovery of novel TGC systems. [ABSTRACT FROM AUTHOR]

PbSe quantum dots (QDs) were used to dope borosilicate glass with a composition of SiO 2 -B 2 O 3 -Al 2 O 3 -ZnO-AlF 3 -Na 2 O-PbO-Se, which was prepared using the conventional melt-quenching technique followed by heat treatment. We observed a broad near infrared (NIR) emission (960–1353 nm) band with a full-width-at-half-maximum (FWHM) value of 168–294 nm and a notable Stokes shift (139–167 nm), which depended on the temperature and duration of the heat treatment. At room temperature, the photoluminescence (PL) lifetime was approximately 1.24–1.92 μs, and it showed a clear dependence on the size and concentration of the QDs. The large FWHM and strong NIR emission of the PbSe QD-doped borosilicate glass may facilitate its application in NIR optical amplifiers and lasers. [ABSTRACT FROM AUTHOR]

• The optical properties of PbSe QDs were regulated by modulating the network topology. • With the incorporation of NaF, the size and concentration of PbSe QDs increased. • The PL intensity of QDs glass is increased by over 14 times under optimal conditions. • Ultra-bandwidth QDs fibers with high luminous efficiency were prepared. Borosilicate glasses doped with PbSe quantum dots (QDs) were prepared by traditional melt-quenching followed by thermal treatment. By introducing a metal fluoride (NaF) network modifier that reduces the number of bridge oxygen bonds, the mobility of Pb2+ and Se2- ions is enhanced during thermal treatment, thereby promoting the precipitation of PbSe QDs. With increasing the thermal treatment temperature or NaF concentration, the absorption peak and emission peak undergo a red shift, which is accompanied by an increase and then decrease of the photoluminescence (PL) intensity, and a gradual increase of the PL lifetime. This evolution in spectral properties is associated with the growth in number and size of PbSe QDs. Furthermore, PbSe QD-doped glass fibers were prepared by a direct drawing method, and the addition of 4 mol % NaF results in an enhancement by 13.5 times in the PL intensity as compared with the fiber fabricated from the glass melt without NaF. Our method could be used to regulate the ultra-wideband near infrared PL of QD-doped glasses, which could find potential applications in ultra-wideband fiber amplifiers. [ABSTRACT FROM AUTHOR]

Abstract: Gold-bowtie nanostructures are fabricated by electron beam lithography and lift-off techniques. Their optical properties are investigated by both experimental studies and numerical simulations. The influence of sharpness and gap of nano-bowtie on optical properties such as extinction cross section, local electric field intensity, and surface resonance wavelength is explored. The experimental extinction spectra agree well with the simulation results. This investigation may help us to design plasmonic sub-wavelength gold-bowtie nanostructure with desired spectral properties. [Copyright &y& Elsevier]

Abstract: Thermal stabilities, absorption spectra, static and transient luminescence spectra, quantum efficiencies were measured and analyzed for the phosphate glasses doped with Tb3+. No fluorescence quenching was observed even when Tb3+ concentration reached 15mol%. The external quantum efficiency of phosphate glass containing 10mol%Tb3+ was measured to be 78%, which is the highest up to date compared with other Tb3+-doped materials reported in previous literatures. The large value of ΔT (Tx – Tg ) of the glasses was about 340°C, which guarantees the thermal stability of the glasses against crystallization during the fiber drawing process, and Tb3+-doped phosphate glass fibers have been successfully drawn. [Copyright &y& Elsevier]

Abstract: The luminescent properties of Eu3+-doped porous glass were investigated and reduction of Eu3+ to Eu2+ was observed when the Eu3+-doped porous glasses were heat treated in air. The absorption, emission and excitation spectra of Eu3+-doped porous glasses were measured and the results significantly depended on the treating temperature. The integral intensity of Eu3+ and Eu2+ ions at different temperatures was also investigated to investigate this reduction process. Electron spin resonance (ESR) spectra of the samples were also measured, which also confirmed the reduction effect. A possible mechanism was discussed to explain this process. [Copyright &y& Elsevier]

Abstract: Phosphate glasses in the compositions of 70P2O5–15Al2O3–14Na2O–1RE3+ (RE=Sm, Dy, and Tm) (mol%) were prepared by melt-quenching technique and characterized optically. The differential thermal analysis (DTA) profile of the host glass was carried out to confirm its thermal stability. For all the glasses absorption, photoluminescence and decay measurements have also been carried out. These glasses have shown strong emission and absorption bands in visible and near-infrared (NIR) region. From the measured absorption spectra, Judd–Ofelt (J–O) intensity parameters (Ω 2, Ω 4 and Ω 6) have been calculated for all the studied ions. For Sm3+ doped glass, four emission bands centered at 562nm (4G5/2 → 6H5/2), 598nm (4G5/2 → 6H7/2), 644nm (4G5/2 → 6H9/2), and 704nm (4G5/2 → 6H11/2) have been observed with 402nm (6H5/2 → 4F7/2) excitation wavelength. Of them, 598nm (4G5/2 → 6H7/2) has shown a bright orange emission. With regard to Dy3+ doped glass, a blue emission band centered at 486nm (4F9/2 → 6H15/2) and a bright yellow emission at 575nm (4F9/2 → 6H13/2) have been observed, apart from 662nm (4F9/2 → 6H11/2) emission transition with an excitation at 388nm (6H15/2 → 4I13/2,4F7/2) wavelength. Emission bands of 650nm (1G4 → 3F4) and 785nm (1G4 → 3H5) transitions for the Tm3+ doped glass, with an excitation wavelength at 466nm (3H6 → 1G4), have also been observed. The stimulated emission cross-sections of all the emission bands of RE3+ glasses (RE=Sm, Dy, and Tm) have been computed based on their measured full-width at half maximum (FWHM, Δλ) and measured lifetimes (τm ). [Copyright &y& Elsevier]

Abstract: In this paper, we present the photoluminescence properties of Pr3+-, Sm3+- and Dy3+-doped germanate glasses and glass ceramics. From the X-ray diffraction measurement, the host glass structure was determined. These glasses have shown strong absorption bands in the near-infrared (NIR) region. Compared to Pr3+-, Sm3+- and Dy3+-doped glasses, their respective glass ceramics have shown stronger emissions due to the Ba2TiGe2O8 crystalline phase. For Pr3+-doped glass and glass ceramic, emission bands centered at 530nm (3P0→3H5), 614nm (3P0→3H6), 647nm (3P0→3F2) and 686nm (3P0→3F3) have been observed with 485nm (3H4→3P0) excitation wavelength. Of them, 647nm (3P0→3F2) has shown bright red emission. Emission bands of 4G5/2→6H5/2 (565nm), 4G5/2→6H7/2 (602nm) and 4G5/2→6H9/2 (648nm) for the Sm3+:glass and glass ceramic, with excitation at 6H5/2→4F7/2 (405nm) have been recorded. Of them, 4G5/2→6H7/2 (602nm) has shown a bright orange emission. With regard to the Dy3+:glass and glass ceramic, a bright fluorescent yellow emission at 577nm (4F9/2→6H13/2) has been observed, apart from 4F9/2→6H11/2 (667nm) emission transition with an excitation at 454nm (6H15/2→4I15/2) wavelength. The stimulated emission cross-sections of all the emission bands of Pr3+, Sm3+ and Dy3+:glasses and glass ceramics have been computed based on their measured full-width at half-maxima (FWHM, Δλ) and lifetimes (τ m). [Copyright &y& Elsevier]

Abstract: New broadband near infrared luminescence covering the whole work windows (1260–1625nm) of the current wavelength division multiplexing (WDM) system was found from bismuth-activated M2O–Al2O3–SiO2 (M=Li, Na) and Li2O–Ta2O5–SiO2 glasses at room temperature in the case of 808nm-laser excitation. But the near infrared luminescence mechanism of the bismuth-activated glasses is not well understood up to now. The figure-of-merits of bandwidth and gain of the glasses are better than those of Er3+-doped silicate glasses and Ti3+ doped sapphire, implying they are the promising gain-medium candidates for the broadband amplifiers and the widely tunable laser sources. [Copyright &y& Elsevier]

Abstract: Yb-doped and Yb–Al-codoped high silica glasses have been prepared by sintering nanoporous glasses. The absorption, fluorescent spectra and fluorescent lifetimes have been measured and the emission cross-section and minimum pump intensities were calculated. Codoping aluminum ions enhanced the fluorescence intensity of Yb-doped high silica glass obviously. The emission cross-sections of Yb-doped and Yb–Al-codoped high silica glasses were 0.65 and 0.82pm2, respectively. The results show that Yb–Al-codoped high silica glass has better spectroscopic properties for a laser material. The study of high silica glass doped with ytterbium is helpful for its application in Yb laser systems, especially for high-power and high-repetition lasers. [Copyright &y& Elsevier]

Abstract: Ag/PPy (polypyrrole) composite colloids were prepared through the reaction of silver nitrate with pyrrole solution in DMF either in the dark, or under the irradiation of femtosecond laser (fs) pulse or UV lamp. The UV–vis spectra of the nanocomposite colloid display an intense absorption band around 620nm, accompanied by a weak one around 470nm. The colors and optical absorption spectra of as-synthesized colloids can be reversibly tuned between blue and red, corresponding to absorption band of 620nm and 526nm, within few seconds by adding base and acid solutions or gases in turn into the composite colloid suspension. In addition, excess of H+ solution enhanced the absorption band around 470nm and, at the same time, depressed that around 620nm. The possible mechanism for the formation and optical absorption properties of the Ag/PPy composite colloid was proposed. [Copyright &y& Elsevier]

Optical nonlinearities of Au nanoparticles precipitated inside glasses induced by irradiation of a focused femtosecond laser were investigated using Z-scan technique with 8 ns pulses at 532 nm. The transformation behaviors both from self-defocusing to self-focusing and from saturable absorption to reverse saturable absorption were observed in the glass samples, which depend drastically on the irradiation power density of the femtosecond laser used. The optical nonlinearities were analyzed in detail and proved numerically by the excited-state theory of conduction band electrons. [Copyright &y& Elsevier]

Investigating the nature of two-/multi-wavelength light excitation effects in optical materials such as their mechanisms, materials composition, and opto-electronic behaviors is crucial for observing the photophysical and photochemical performance for their applications. Recently, this research area has received extensive attention owing to its remarkable optical performance, capability of tunable fluorescence emission, tailorable photochemical reaction, controllable electron population, and driving of novel photophysical and photochemical phenomena, which are promising for emerging applications in broad areas of spectroscopy, photophysics, photochemistry, opto-electronics, biophysics, as well as environmental and materials science. In this work, we review recent progress in the interdisciplinary studies of photoluminescence mechanisms, emitting centers, host material system, optical setups and characterization techniques, and application fields for the optical materials by two-/multi-wavelength light excitation effects. In the first part, we introduce the latest progress of two-/multi-wavelength light excitation effects in optical materials, from their fundamentals to their applications. In the second part, we present the dominant two-/multi-wavelength excited photoluminescence mechanisms, including excited state absorption, stimulated emission depletion (STED), ground state depletion, and more STED-inspired models. Moreover, we outline recent progress in optically active centers and host material classification, and their intrinsic connections between tunable microstructures and applications for different material systems based on two-/multi-wavelength light excitation effects. Optical measurement setups and characterization techniques for broad application fields are reviewed and summarized. By emphasizing the progress of emerging photoluminescence properties in optical materials and their application prospects based on two-/multi-wavelength light excitation effects, involving three-dimensional displays, lasers, STED super-resolution nanoscopy, photolithography and optical data storage, ultraviolet bacteriostatic agents, solar cells, and optical switches are explained. Finally, we discuss the present achievements and remaining questions and provide perspectives for future research directions. [ABSTRACT FROM AUTHOR]