Laser emission and amplification at 1.3 mu m in neodymium-doped fluorophosphate fibres

Laser emission and amplification have been studied in the 1.3 mu m spectral region on the /sup 4/F/sub 3/2/-/sup 4/I/sub 13/2/ transition in Nd/sup 3+/-doped fluorophosphate singlemode fibres. Pumping at 800 nm yields an extracted laser power of 10 mW at 1.323 mu m. A gain higher than 3 dB was obtained at the same wavelength in the amplifier experiment.<>     

The influence of pump wavelength on Er:YAG Green-emitting laser characteristics

Mathematical modeling is used to study the influence of pump wavelength on the emission of an Er(0.5 at.%):YAG laser on the transition /sup 4/S/sub 3/2//spl rarr//sup 4/I/sub 15/2/ (561 nm). Three pump wavelengths (direct pumping: 488 nm, upconversion pumping: 800 and 810 nm) are investigated and the corresponding laser emission regimes are discussed. For upconversion pumping, we find an optimum pump wavelength and optimum resonator losses for lowering of the continuous-wave emission threshold.     

复合腔和频554.8 nm黄-绿光激光器

介绍了一种光纤耦合激光二极管阵列(LDA)同时泵浦Nd:YAG和Nd:YVO4晶体输出554.8nm连续波的全固态黄-绿光激光器。黄-绿激光是由Nd:YAG晶体的946nm激光和Nd:YVO4晶体的1342nm激光非线性和频产生,两条谱线在各自晶体的对应能级跃迁分别为4F3/2-4I9/2和4F3/2-4I13/2。实验中采用复合腔结构,利用KTP晶体II类临界相位匹配进行腔内和频,当注入到Nd:YAG和Nd:YVO4晶体的泵浦功率分别为30W和20W时,获得了1.13W的连续波554.8nm黄-绿激光输出,光束质量因子M2<1.22,这是目前为止该波长已见报道的最高功率输出值。实验结果表明:采用Nd∶YAG和Nd∶YVO4两种激光晶体进行腔内和频是获得黄-绿激光的高效方法,并可以应用到其他两种激光晶体进行腔内非线性和频,获得更多不同波长的激光输出。     

Silica-clad neodymium-doped lanthanum phosphate fibers and fiber lasers

We have fabricated a neodymium-doped phosphate glass fiber with a silica cladding and used it to form a fiber laser. Phosphate and silicate glasses have considerably different glass transition temperatures and softening points making it hard to draw a fiber from these two glasses. A bulk phosphate glass of composition (Nd/sub 2/O/sub 3/)/sub 0.011/(La/sub 2/O/sub 3/)/sub 0.259/(P/sub 2/O/sub 5/)/sub 0.725/(Al/sub 2/O/sub 3/)/sub 0.005/ was prepared and the resultant material was transparent, free from bubbles and visibly homogeneous. The bulk phosphate glass was drawn to a fiber while being jacketed with silica and the resultant structure was of good optical quality, free from air bubbles and major defects. The attenuation at a wavelength of 1.06 /spl mu/m was 0.05 dB/cm and the refractive index of the core and cladding at the pump wavelength of 488 nm was 1.56 and 1.46, respectively. The fibers were mechanically strong enough to allow for ease of handling and could be spliced to conventional silica fiber. The fibers were used to demonstrate lasing at the /sup 4/F/sub 3/2/-/sup 4/I/sub 11/2/ (1.06 /spl mu/m) transition. Our work demonstrates the potential to form silica clad optical fibers with phosphate cores doped with very high levels of rare-earth ions (27-mol % rare-earth oxide).     

Characterization of diode-pumped laser operation of a novel Yb:GSO Crystal

We report what is believed to be the first demonstration of the laser action of Yb/sup 3+/-doped Gd/sub 2/SiO/sub 5/ (Yb:GSO)crystal pumped by a 940-nm laser diode at room temperature. The threshold of laser generation is only 0.85 kW/cm/sup 2/, which is smaller than the theoretic threshold of Yb:YAG (1.54 kW/cm/sup 2/). The laser wavelength is 1090 nm. With a 2.5% output coupler, the maximum output power is 415 mW under a pump power of 5W. By using the SESAM, the Q-switched modelocking and CW mode-locked operations are demonstrated.     

全固态复合内腔和频613nm连续波橙光激光器

报道了全固态连续波613nm橙光激光器,橙激光是分别由Nd:YAG和Nd:YVO4晶体的1444nm和1064nm谱线非线性和频产生的,两条谱线在各自晶体对应能级跃迁分别为4F3/2-4I13/2和4F3/2-4I11/2.实验中采用复合腔结构,利用KTP晶体Ⅱ类临界相位进行内腔和频,当注入到Nd:YAG和Nd:YVO4晶体的泵浦功率分别为20W和10W时,获得344mW的TEM00连续波613nm橙激光输出.4h功率稳定度优于±2.8%.     

Multi-watt, high efficiency, diffraction-limited Nd:YAG planar waveguide laser

An efficient, longitudinally diode-pumped, diffraction-limited, Nd:YAG double-clad planar waveguide laser was operated on four transitions of the Nd/sup 3+/ ion. Optimized output powers of 4.3, 3.5, and 2.7 W were obtained for absorbed pump powers of /spl sim/7 W, for the transitions at the lasing wavelengths of 1.064 /spl mu/m, 946 nm, and 1.3 /spl mu/m, respectively. Operation of the weak /sup 4/F/sub 3/2//spl rarr//sup 4/I/sub 5/2/ transition, lasing at 1.833 /spl mu/m, was demonstrated at an absorbed pump power threshold of 300 mW and an output power of 400 mW, with a nonoptimized output coupling. Diffraction-limited performance was obtained in both the guided and nonguided axes.     

双波长晶体激光器

本文介绍了烈波长晶体激光器的概况, 重点描述了我们在双波长晶体激光器方面的研究工作。这些工作如下:建立了多波长激光器的振荡条件, 用它分析、比较了Nd:YAG, Nd:YLF, Nd:BEL和Nd:YAlO3(Nd:YAP)等晶体实现4F3/2-4I11/2和4F3/2-4I13/2跃迁双波长激光的可能性, 分析表明上述晶体均能实现脉冲双波长激光.但只有Nd:YAP晶体能实现连续双波长激光运转。根据这判断, 我们利用Nd:YAP晶体, 首次获得了晶体双波长连续激光, l079.5 nm和1341.4 nm输出功率分别选23.9 W和25.4 W。并研制成Nd:YAG和大能黄Nd:YAP双波长激光器 实验表明, 这二种激光器中二个波长的输出具有较好的时间和空间的重叠性 此外, 我们还研制成1655 nm和1663 nm双渡长及271l nm, 2730 nm和2790 nm三波长Er:YAP脉冲激光器。     

850mW全固态腔内和频554．9nm连续黄光激光器

报道了全固态连续波554．9nm黄光激光器,黄激光是分别由Nd：YAG和Nd：YVO4晶体的1342nm和946nm谱线非线性和频产生,两条谱线在各自晶体对应能级跃迁分别为^4F3/2-^4I11／2和^4F3／2-^4I9/2。实验中采用复合折叠腔结构,利用LBO晶体I类临界相位进行内腔和频,当注入到Nd：YAG和Nd：YVO4晶体的泵浦功率分别为20W和8W时,获得850mW的TEMoo连续波554．9nm黄激光输出。4小时功率稳定度优于±2．5%.     

激光二极管阵列抽运Nd∶YAG腔内双波长运转589nm和频激光器

报道了一种光纤耦合激光二极管阵列(LDA)抽运Nd∶YAG晶体、腔内Ⅰ类临界相位匹配LBO和频、连续波输出的全固态589 nm激光器的设计和实验结果。黄激光是由Nd∶YAG晶体的1064 nm和1319 nm谱线腔内和频产生的,其对应能级跃迁分别为4F3/2→4I11/2和4F3/2→4I13/2。实验采用三镜折叠腔结构,在808 nm的15 W抽运功率下,获得了最高功率为860 mW连续波TEM00的589 nm黄激光输出,光-光转换效率为5.7%,激光输出功率噪声低,光束质量因子M2<1.2,4 h功率稳定度优于±3.4%。实验结果表明采用三镜折叠腔进行腔内和频是获得589 nm黄激光的有效方法,并可以应用到Nd∶YAG晶体的其他谱线或具有多条谱线的其他激光增益介质,获得更多不同波长激光输出。     

Passive Q-switching of an intracavity frequency doubled diode-pumped Nd:YVO/sub 4//KTP green laser with Cr/sup 4+/:YAG

A compact diode-pumped green-pulse laser has been demonstrated by using Cr/sup 4+/:YAG as a saturable absorber in a simple cavity formed by a coated Nd:YVO/sub 4/ crystal and a coated KTP crystal. When continuous-wave (CW) pumped with a fiber-coupled laser diode, the laser produces green pulses of 20-35-ns duration at 532 nm, with a repetition rate of 15-70 kHz. The highest green peak power was 80.8 W, obtained at 1.2 W of pump power, which is 320 times enhancement in comparison to a green output power of 250 mW under CW.     

Multiwavelength diode-cladding-pumped Nd/sup 3+/-doped germano-aluminosilicate fiber laser

Simultaneous multiwavelength oscillation at 1060 and 1090 nm has been produced from a free-running Nd/sup 3+/-doped multicomponent silica fiber laser. As a result of co-doping with both Al/sub 2/O/sub 3/ and GeO/sub 2/, the Nd/sup 3+/ ions are situated at separate sites relating to either Al/sup 3+/-rich or Ge/sup 4+/-rich regions of the germano-aluminosilicate glass. The slope efficiency of the combined /spl sim/1-/spl mu/m output was /spl sim/52% (56%) with respect to the launched (absorbed) pump power. The 1060-nm emission reaches threshold first because of the greater number of Nd/sup 3+/ ions that are located at Al/sup 3+/-rich sites. On chopping the pump light the relaxation oscillations relating to the 1090-nm emission are antiphase with the oscillations observed with the 1060-nm emission. A degree of spectral overlap exists between the fluorescence emitted from Nd/sup 3+/ ions located at each site. Power equalization (to /spl sim/1 W each) of the 1060- and 1090-nm emissions was carried out by way of Raman amplification that occurred either internally or externally to the Nd/sup 3+/-doped silica fiber laser.     

Amplification and lasing at 1.3 mu m in praseodymium-doped fluorozirconate fibres

Light emission from the /sup 1/G/sub 4/ to /sup 3/H/sub 5/ transition around 1.3 mu m of Pr/sup 3+/ has been studied in fluoride glass (ZBLAN) fibres. Pumping at 1064 nm yields extracted laser power of a few mW at 1.294 mu m. Gain curves centred at 1.295 mu m have been obtained, with gross gains of more than 15 dB at 1.319 mu m. Changes of the output ASE with pumping conditions are explained by excited state absorption or energy transfer from the /sup 1/G/sub 4/ upper level of the transition.<>     

Fabrication of Germanosilicate glass optical fibers containing Tm/sup 2+/ ions and their nonlinear optical properties

Germanosilicate glass optical fibers incorporated with the Tm/sup 2+/ ions were fabricated to enhance optical nonlinearity by providing a strong reduction environment based on the solution doping technique in the modified chemical vapor deposition (MCVD) process. The incorporation of the Tm/sup 2+/ ions into the fiber core was identified by the electron paramagnetic resonance (EPR) spectrum in the fiber preform, and the absorption and emission properties between 350 and 1600 nm of the Tm/sup 2+/ ions in optical fibers and the fiber preform. A strong broad absorption band due to the Tm/sup 2+/ ions appeared from 350 to /spl sim/900 nm, and a broad emission from /spl sim/600 to /spl sim/1050 nm and the other emission from /spl sim/1050 to /spl sim/1300 nm, which were not shown in the Tm/sup 3+/ ions, were found upon Ar-ion laser pumping at 515 nm. Both absorption and emission results confirm that the Tm/sup 2+/ ions in the germanosilicate glass have the 4f-5d energy band from 350 to /spl sim/900 nm and the 4f-4f energy level at /spl sim/1115 nm. Also, the resonant nonlinearity at /spl sim/1310 and /spl sim/1530 nm due to the Tm/sup 2+/ ions in the fiber was measured upon the 515 nm optical pumping by using a long-period fiber grating (LPG) pair method. The nonlinear refractive index n/sub 2/ at /spl sim/1310 and /spl sim/1530 nm was found to be /spl sim/4/spl times/10/sup -15/ m/sup 2//W, where 70% and 30% of the n/sub 2/ are attributed to the nonradiative transitions and the radiative transitions, respectively.     

Measurement of gain, group index, group velocity dispersion, and linewidth enhancement factor of an InGaN multiple quantum-well laser diode

Gain, group index, group velocity dispersion (GVD), temperature variation of refractive index, and linewidth enhancement factor of an In/sub 0.15/Ga/sub 0.85/N/In/sub 0.02/Ga/sub 0.98/N multiple quantum-well blue laser diode was measured using the Fourier transform method as a function of wavelength from 400 to 410 nm. At the lasing wavelength (403.5 nm), the group index is 3.4, the GVD (dn/sub g//d/spl lambda/) is -37 /spl mu/m/sup -1/, the temperature variation of refractive index dn/dT is 1.3/spl times/10/sup -4/ K/sup -1/, and the linewidth enhancement factor is 5.6.     

Spectroscopic analysis and diode-pumped laser results of Nd:BaY/sub 2/F/sub 8/

Single crystals of monoclinic BaY/sub 2/F/sub 8/, doped with different Nd/sup 3+/ concentrations, were successfully grown by means of the Czochralski method. Here, we present a polarized infrared (IR) spectroscopic investigation and diode-pumped continuous-wave laser results in the 1 /spl mu/m wavelength region. Moreover for the first time 1.3 /spl mu/m laser emission has been characterized. Q-switching results in the 1-/spl mu/m region are also presented.     

Semiconductor laser pumping of continuous-wave Pr/sup 3+/-doped ZBLAN fibre laser

Blue semiconductor laser pumped continuous-wave laser oscillation of a Pr-doped ZrF/sub 4/-BaF/sub 2/-LaF/sub 3/-AlF/sub 3/-NaF fibre in the red spectral range is reported for the first time. The pump power is provided by a frequency-doubled optically pumped semiconductor laser system. When pumped with 300 mW at a wavelength of 479.7 nm, the Pr/sup 3+/-laser emitted 94 mW of output power at a wavelength of 635 nm. Threshold pump power and slope efficiency with respect to the incident pump power were determined to be 49.7 mW and 41.5%, respectively.     

全固态593 nm复合腔连续波和频激光器

报道了一种新型复合腔结构和频(SFM)激光器,用两个激光二极管阵列(LDA)经过光纤耦合分别单独端面抽运Nd∶YVO4晶体,其中两激光晶体所选择的能级跃迁分别为4F3/2→4I11/2和4F3/2→4I13/2,其对应激光跃迁波长分别为1064nm和1342nm,两基频激光束分别在两个子谐振腔中振荡,在其交叠区利用KTPⅡ类临界相位匹配(CPM)进行腔内和频,获得了593nm的和频激光。通过对激光晶体热效应的分析,设计了热不敏感腔,获得了520mW连续波(CW)TEM00黄激光输出。光束质量因子M2<1.2,激光输出为低噪声输出,24h功率不稳定度小于±2%。     

Continuous-wave laser oscillation of Yb/sup 3+/ in monoclinic KLu(WO/sub 4/)/sub 2/

The strongly anisotropic monoclinic double tungstate crystal KLu(WO/sub 4/)/sub 2/ was doped with Yb/sup 3+/ ions and shown to be a highly efficient active laser medium in the 1-/spl mu/m spectral range for continuous-wave room-temperature operation, very suitable for pumping with InGaAs laser diodes.     

Highly efficient picosecond Raman generators based on the BaWO/sub 4/ crystal in the near infrared, visible, and ultraviolet

The stimulated Raman scattering process in a BaWO/sub 4/ crystal was employed to frequency downshift the first, second, and third harmonics of a Nd:YAG actively-passively mode-locked laser system. Single-pass, double-pass, and external cavity configurations were investigated for this purpose. In each experimental arrangement, the Stokes radiation properties were characterized regarding energy, beam profile, spectrum, and temporal development. The peak pump-to-first-Stokes conversion efficiency was measured to be 55% in the near infrared and 85% in the visible spectral region. The BaWO/sub 4/ picosecond Raman gain at a pump wavelength of 355 nm was measured to be 38 cm/GW, and a 15% conversion efficiency was achieved. A study of the Raman-cavity output beam profile development as a function of pumping energy was conducted. This work shows that the BaWO/sub 4/ crystal can be used in picosecond solid-state laser systems as an efficient frequency converter with a wide range of pump radiation wavelengths.