Stabilization of optical Fabry-Perot sensor by active feedback control of diode laser

This paper presents the design and characterization of a fiber Fabry-Perot interferometer (FFPI) acoustic wave detector with its Q point being stabilized actively. The relationship between the reflectivity of the F-P cavity facets and cavity length was theoretically analyzed, and high visibility of 100% was realized by optimized design of the F-P cavity. To prevent the drifting of the Q point, a new stabilization method by actively feedback controlling of the diode laser is proposed and demonstrated, indicating the method is simple and easy operating. Measurement shows that good tracing of Q point was effectively realized. (c) 2008 Elsevier B.V. All rights reserved.

Study of near-infrared nonvolatile two-center holographic recording in LiNbO3:Fe:Rh crystal

The near-infrared nonvolatile holographic recording has been realized in a doubly doped LiNbO3:Fe:Rh crystal by the traditional two-center holographic recording scheme, for the first time. The recording performance of this crystal has been investigated by recording with 633 nm red light, 752 nm red light and 799 nm near-infrared light and sensitizing with 405 nm purple light. The experimental results show that, co-doped with Fe and Rh, the near-infrared absorption and the photovoltaic coefficient of shallow trap Fe are enhanced in this LiNbO3:Fe:Rh crystal, compared with other doubly doped LiNbO3 crystals Such as LiNbO3:Fe:Mn. It is also found that the sensitizing light intensity affects the near-infrared recording sensitivity in a different way than two-center holographic recording with shorter wavelength, and the origin of experimental results is analyzed. (C) 2007 Elsevier GrnbH. All rights reserved.

A planar waveguide Nd : YAG laser using active Q-switching of a hybrid unstable resonator

A planar waveguide laser operating in a negative branch unstable resonator is Q-switched by an acoustooptic mod latorin anew configuration, providing effective, high-speed switching. The laser using a 200-mu m Nd:YAG core, face pumped by 10 laser diode bars, has produced 100-W output in a good beam quality at 100-kHz pulse rate, and 4.5 mJ at lower frequency with 15-ns pulse duration.

Infrared-to-visible upconversion emissions in Er3+ doped TeO2-based oxyhalide glasses

The fluorescence and up-conversion spectral properties of Er3+-doped TeO2-ZnO and TeO2-ZnO-PbCl2 glasses suitable for developing optical fiber amplifier and laser have been fabricate and characterized. Strong green (around 527-550 nm) and red (around 661 nm) up-conversion emissions under 977 nm laser diode excitation were investigated, corresponding to H-2(11/2), S-4(3/2), --> I-4(15/2) and F-4(9/2) --> I-4(15/2) transitions of Er3+ ions respectively, have been observed and the involved mechanisms have been explained. The dependence of up-converted fluorescence intensity versus laser power confirm that two-photons contribute to up-conversion of the green-red emissions. The novelty of this kind of optical material has been its ability in resisting devitrification, and its promising optical properties strongly encourage for their further development as the rare-earth doped optical fiber amplifiers and upconversion fiber laser systems.

Near infrared broadband emission from bismuth-dysprosium codoped chalcohalide glasses

We investigate the broadband infrared emission of bismuth doped and bismuth/dysprosium codoped chalcohalide glasses. It is found that the bismuth/dysprosium codoping can drastically enhance the fluorescence as compared with either bismuth or dysprosium doped glasses. Meanwhile, the full width at half maximum of bismuth/dysprosium codoped glasses is over 170 nm, which is the largest value among all the reported rare-earth doped chalcohalide glasses. An ideal way for energy consumption between bismuth and dysprosium ions is supposed. Such improved gain spectra of both bismuth and dysprosium ions may have potential applications in developing broadband fibre amplifiers.

Ultrabroadband infrared luminescence and optical amplification in bismuth-doped germanosilicate glass

This letter reports the ultrabroadband infrared luminescence from 1000- to 1700-nm wavelength range and demonstrate optical amplification at the second optical communication window in a novel bismuth-doped germanosilicate glass. The full-width at half-maximum of the luminescence is about 300 mn and the optical gain is larger than 1.37 within the wavelength region from 1272 to 1348 nm with pump power 0.97 W. This material could be useful to fabricate ultrabroadband optical fiber amplifiers.

Effects of melting temperature on the broadband infrared luminescence of bi-doped and Bi/Dy co-doped chalcohalide glasses

Bismuth (Bi)-doped and Bi/Dy co-doped chalcohalide glasses are investigated as promising materials for amplifiers in optical communication. The samples synthesized at lower melting temperatures (MTs) are characterized by more intensified infrared emissions. With respect to the redox process of a liquid mixture at different MTs, we attribute an emission at 1230 nm to low-valent Bi ions. The lower MT favors the formation of LVB ions, i.e. Bi+ or Bi2+, while the higher MT promotes the production of higher-valent Bi ions Bi3+. An enhanced broadband infrared luminescence with the full-width at half-maximum over 200 nm is achieved from the present Bi/Dy co-doped chalcohalide glasses.

Broadband near-infrared emission from transparent Ni2+-doped silicate glass ceramics

Transparent Ni2+-doped MgO-Al2O3-TiO2-SiO2 glass ceramics were prepared, and the optical properties of Ni2+-doped glass ceramics were investigated. Broadband emission centered at 1320 nm was observed by 980 nm excitation. The longer wavelength luminescence compared with Ni2+-doped Li2O-Ga2O3-SiO2 glass ceramics is ascribed to the low crystal field hold by Ni2+ in MgO-Al2O3-TiO2-SiO2 glass ceramics. The change in optical signals at the telecommunication bands with or without 980 nm excitation was also measured when the seed beam passes through the bulk gain host.(C) 2007 American Institute of Physics.

Ultrabroad infrared luminescences from Bi-doped alkaline earth metal germanate glasses

We report on ultrabroad infrared (IR) luminescences covering the 1000-1700-nm wavelength region, from Bi-doped 75GeO(2) 20RO-5Al(2)O(3) 1B(2)O(3) (R = Sr, Ca, and Mg) glasses. The full width at half-maximum of the IR luminescences excited at 980 nm increases (315 -> 440 -> 510 nm) with the change of alkaline earth metal (Mg2+ -> Ca2+ -> Sr2+). The fluorescence lifetime of the glass samples is 1725, 157, and 264 mu s when R is Sr, Ca, and Mg, respectively. These materials may be promising candidates for broad-band fiber amplifiers and tunable laser resources.

Intense infrared luminescence in transparent glass-ceramics containing beta-Ga2O3 : Ni2+ nanocrystals

Transparent glass-ceramics containing beta-Ga2O3:Ni2+ nanocrystals were synthesized and characterized by X-ray diffraction, transmission electron microscopy, and electron energy loss spectroscopy. Intense broad-band luminescence centering at 1200 nm was observed when the sample was excited by a diode laser at 980 nm. The room-temperature fluorescent lifetime was 665 mu s, which is longer than the Ni2+-doped ZnAl2O4 and LiGa5O8 glass-ceramics and is also comparable to the Ni2+-doped LiGa5O8 single crystal. The intense infrared luminescence with long fluorescent lifetime may be ascribed to the high crystal field hold by Ni2+ and the moderate lattice phonon energy of beta-Ga2O3. The excellent optical properties of this novel material indicate that it might be a promising candidate for broad-band amplifiers and room-temperature tunable lasers.

Transparent Ni2+-doped lithium-alumino-silicate glass-ceramics for broadband near-infrared light source

Broadband infrared luminescence centred at around 1300 nm with full-width at half maximum of about 342 nm was observed from transparent Ni2+-doped lithium-alumino-silicate glass-ceramics embedded with beta-eucryptite crystallines. The room temperature fluorescent lifetime was 98 mu s. The transparent glass-ceramics may have potential applications in a widely tunable laser and a super-broadband optical amplifier for optical communications.

New transparent Er3+-doped oxyfluoride tellurite glass ceramic with improved near infrared and up-conversion fluorescence properties

Transparent glass ceramics have been obtained by nucleation and growth of Y2Te6O15 or Er2Te5O13 cubic phase in a new Er3+-doped oxyfluoride tellurite glass. Effect of beat treatment on absorption spectra, luminescence and up-conversion properties in the oxyfluoride tellurite glass has been investigated. With heat treatment the ultraviolet absorption edge red shifted evidently for the oxyfluoride telluride glass. The near infrared emission that corresponds to Er3+:I-4(13/2)-> I-4(15/2) can be significantly enhanced after heat treatment. Under 980 nm LD pumping, red and green up-conversion intensity of Er3+ in the glass ceramic can be observed much stronger than that in the base glass. (C) 2006 Elsevier B.V. All rights reserved.

Bismuth-doped zinc aluminosilicate glasses and glass-ceramics with ultra-broadband infrared luminescence

Broadband infrared luminescence covering the optical telecommunication wavelength region of 0, E and S bands was observed from bismuth-doped zinc aluminosilicate glasses and glass-ceramics. The spectroscopic properties of the glasses and glass-ceramics depend on the thermal-treatment history. With the appearance of gahnite (ZnAl2O4) crystalline phase, the fluorescent peak moves to longer wavelength, but the fluorescent intensity decreases. The similar to 1300 nm fluorescence with a FWHM larger than 250 nm and a lifetime longer than 600 mu s possesses these optical materials with potential applications in laser devices and broadband amplifiers. The broad infrared luminescence from the bismuth-doped zinc aluminosilicate glasses and glass-ceramics might be from BiO or bismuth clusters rather than from Bi5+ and Bi3+. (c) 2005 Elsevier B.V. All rights reserved.

Ultrabroad infrared luminescence from Bi-doped aluminogermanate glasses

We report ultrabroad infrared luminescence from Bi-doped aluminogermanate glasses. The infrared luminescence almost covers the whole low loss wavelength region (1200-1650 nm) of silica glass fiber when excited by a diode laser at 980 nm. The full width at half maximum (FWHM) of the luminescence is 510 nm. The luminescence peak can be divided into three Gaussian peaks, and the fluorescence lifetime of the three emissions are 297 mu s, 470 mu s and 1725 mu s, respectively. These fluorescence properties indicate that the glasses are promising material for broadband optical amplifiers. (C) 2007 Elsevier Ltd. All rights reserved.

高硅氧发光玻璃的制备及其荧光性能

abstract {Silica glass is an attractive host matrix for the emission ions of rare earth and transition metal ions because it has small thermal expansion coefficient, strong thermal resistance, large fracture strength and good chemical durability and so on. However, a major obstacle to using it as the host matrix is a phenomenon of concentration quenching. In this paper, we introduces a novel method to restrain the concentration quenching by using a porous glass with SiO₂ content > 95% (in mass) and prepare intense fluorescence high-SiO₂ glasses and high-SiO₂ laser glass. The porous glass with high-SiO₂ content was impregnated with rare-earth and transition metal ions, and consequently sintered into a compact non-porous glass in reduction or oxidization atmospheres. Various intense fluorescence glasses with high emission yields, a vacuum ultraviolet-excited intensely luminescent glass, high silica glass containing high concentration of Er³⁺ ion, ultrabroad infrared luminescent Bi-doped high silica glass and Nd³⁺-doped silica microchip laser glass were obtained by this method. The porous glass is also favorable for co-impregnating multi-active-ions. It can bring effective energy transferring between various active ions in the glass and increases luminescent intensity and extend range of excitation spectrum. The luminescent active ions-doped high-SiO₂ glasses are potential host materials for high power solid-state lasers and new transparent fluorescence materials.}