High power 1341.4 nmNd:YAlO3 CW laser and its performances

A lamp pumped high power 1341.4 nmNd:YAlO₃CW laser and its performances have been described. As high as 188 W of CW output power has been obtained at 1341.4 nm alone line with a overall efficiency of 1.37% and a slope efficiency of 2.14%. The divergence (FWHM) and instability (RMS) of this laser at output power of 155 W are 15 mrad and 1.19%, respectively.     

Diode-pumped short pulse passively Q-switched 912 nm Nd:GdVO<Subscript>4</Subscript>/Cr:YAG laser at high repetition rate operation

A diode-end-pumped passively Q-switched 912 nm Nd:GdVO₄/Cr:YAG laser is demonstrated for the first time. In a concave-piano cavity, pulsed 912 nm laser performance is investigated using two kinds of Cr:YAG crystal with different unsaturated transmission (T _U) of 95% and 90% at 912 nm as the saturable absorbers. When the T _U = 90% Cr:YAG is used, as much as 2.6 W average output power for short pulsed 912 nm laser is achieved at an absorbed pump power of 34.0 W, corresponding to an optical efficiency of 7.6% and a slope efficiency of 20.3%. Moreover, 10.5 ns duration pulses and up to 2.3 kW peak power is obtained at the repetition rate around 81.6 kHz.     

1444-nm Q-switched pulse generator based on Nd:YAG/V:YAG microchip laser

Q-switched microchip laser emitting radiation at eye-safe wavelength 1444 nm was designed and realized. This laser was based on composite crystal which consists of 4 mm long Nd:YAG active medium diffusion bonded with 1 mm long V:YAG saturable absorber. The diameter of the composite crystal was 5 mm. The initial transmission of the V:YAG part was T ₀ = 94% @ 1440 nm. The microchip resonator consists of dielectric mirrors, directly deposited onto the composite crystal surfaces. These mirrors were specially designed to ensure desired emission at 1444 nm and to prevent parasitic lasing at other Nd³⁺ transmissions. The output coupler with reflectivity 94% for the generated wavelength 1444 nm was placed on the V³⁺-doped part. The laser was operating under pulsed pumping for the duty-cycle up to 50%. With increasing value of mean pumping power a strong decrease of generated pulse length was observed. The shortest generated pulses were 4.2 ns long (FWHM). Stable pulses with energy 34 μJ were generated with repetition rate up to 1.5 kHz. Corresponding pulse peak power was 8.2 kW. The wavelength of linearly polarized TEM₀₀ laser mode was fixed to 1444 nm.     

KGW 晶体外腔式高功率579 nm喇曼黄光激光器

报道了579 nm高功率KGd(WO₄)₂喇曼晶体外腔式喇曼黄光激光器的输出特性.基于808 nm脉冲激光二极管侧面泵浦Nd:YAG陶瓷、腔内BBO电光晶体同步延迟调Q和Ⅰ类临界相位匹配的LBO晶体腔外倍频方案,并通过外腔式KGW晶体Ng轴二阶斯托克斯喇曼频移,获得了579.54 nm黄光激光输出.当脉冲信号重复频率为1 kHz、532 nm泵浦光最高平均功率为5.02 W、脉冲宽度为10.1 ns时,获得了最高平均功率2.58 W、脉冲宽度7.4 ns、峰值功率348.6 kW的579.54 nm二阶斯托克斯喇曼黄光激光输出;532 nm至579.54 nm的光-光转化效率为51.4%、斜率效率为54.8%,光束质量因子M_x-579.54²=5.829、M_y-579.54²=6.336,输出功率不稳定性小于±2.35%.实验表明:外腔式喇曼结构能够高效地获得喇曼黄光,具有很高的光-光转化效率及良好的功率稳定性,并通过脉冲LD结合同步延迟电光调Q可获得高重复频率、高平均功率、窄脉冲宽度和高峰值功率的黄光激光输出.     

Completely solid-state LD-side-pumped Nd:YAlO<Subscript>3</Subscript> CW blue laser with intracavity frequency tripling

We report a completely solid-state continuous-wave (CW) blue laser operating at 447 nm utilizing intracavity frequency tripling of an LD-side-pumped Nd:YAlO₃ (Nd:YAP) laser operating at 1341.4 nm. An LBO crystal with type-I critical phase matching and a KTP crystal with type-II critical phase matching (CTM) were used for the second harmonic generation (SHG) and the third harmonic generation (THG), respectively. In view of the analysis of the cavity stability, a four-mirror folded cavity was designed and the output characteristics were theoretically analyzed. Experimental characteristics obtained were shown to be in agreement with the theoretical analysis. The maximum output power of the 447 nm CW blue laser reached 114 mW, which corresponds to a red-to-blue conversion efficiency of 9%.     

Continuous wave operation of singly-doped Ho:LSO laser at room temperature

We present the room-temperature continuous-wave Ho:LSO laser single-pass-end-pumped by a diode-pumped Tm:YLF laser at 1.91 μm in this paper. Under different output couplers of 2.4, 5.0, and 14.0%, the laser output power and output spectrum of Ho:LSO laser operating at room temperature are investigated. The output wavelength of Ho:LSO laser was centered at 2106.5 nm with linewidth (FWHM) of about 3.2 nm. With T = 5.0%, the maximum output power of 2.4 W was achieved under the absorbed pump power of 11.1 W, corresponding to a slope efficiency of 38.0%.     

8.1 W/670.7 nm and 5.1 W/669.6 nm cw red light outputs by intracavity frequency doubling of a Nd:YAP laser with LBO

In this paper, the continuous-wave intracavity second harmonic generation of a laser diode side-pumped Nd:YAP laser operating in the 1.3-μm region is demonstrated. A type-I critical phase-matched LiB₃O₅ (LBO) crystal was used as the frequency doubler. 8.1 W/670.7 nm and 5.1 W/669.6 nm continuous-wave red light outputs were achieved from the 1341.4-nm laser beam polarized along the c crystalline axis and the 1339.2-nm laser beam polarized along the a crystalline axis, respectively. The stability of the 670.7-nm red laser is better than 3% at the output power of 7 W in an hour.     

Quasi-three-level Nd:YVO<Subscript>4</Subscript> laser by diode pumping at 888 nm

We report efficient laser emission on the 914 nm ⁴ F _3/2 to ⁴ I _9/2 transition in Nd:YVO₄ under the pump with diode lasers at 888 nm for the first time. Continuous wave 6.57 W output power at 914 nm is obtained from a V-type resonator under 18.3 W of absorbed pump power; the slope efficiency with respect to the absorbed pump power was 60.6%. Moreover, intracavity frequency doubling with BiB₃O₆ (BiBO) nonlinear crystal yielded 1.77 W of deep-blue light at 457 nm with beam quality characterized by an M₂ factor of 1.25.     

高稳定LD泵浦腔内倍频Nd∶YVO4/KTP连续绿光激光器

设计出一种能够较好地补偿激光晶体热效应的激光谐振腔，实现了高稳定LD单端泵浦KTP腔内倍频Nd∶YVO₄连续绿光激光器.当晶体吸收的泵浦功率为24.56 W时，532 nm激光功率达到5.3 W，光-光转换效率达到21.6％，激光模式为TEM00模.在输出功率5W左右时，激光器1 h功率不稳定度优于0.6％     

Continuous-wave high-power Nd:YAG-KNbO3 laser at 473 nm

A continuous-wave high-power Nd:YAG laser operating on the ⁴F_3/2→⁴I_9/2 transition at 946 nm and intracavity frequency-doubled to 473 nm by a KNbO₃ nonlinear crystal at room temperature is reported. The Nd:YAG laser outputs a randomly polarized beam of 3.8 W maximum power (38% optical-to-optical efficiency and 44% slope efficiency with respect to the absorbed pump power) at the 946 nm fundamental wavelength. Intracavity frequency-doubling with a 2.0-mm thick KNbO₃ crystal in a linear resonator yielded 159-mW single-ended blue-output with 4.8% optical-to-optical conversion efficiency versus the absorbed pump power. The 473-nm maximum power of 418 mW with 11.6% optical-to-optical conversion efficiency in absorbed power was obtained from a V-type resonator; the overall optical-to-optical conversion efficiency was 6.7%, while the conversion of the available infrared power reached 50%.     

High-power linearly-polarized tunable Raman fiber laser

In this study, we demonstrate an all-fiber high-power linearly-polarized tunable Raman fiber laser system. An inhouse high-power tunable fiber laser was employed as the pump source. A fiber loop mirror(FLM) serving as a high reflectivity mirror and a flat-cut endface serving as an output coupler were adopted to provide broadband feedback. A piece of 59-m commercial passive fiber was used as the Raman gain medium. The Raman laser had a 27.6 nm tuning range from1112 nm to 1139.6 nm and a maximum output power of 125.3 W, which corresponds to a conversion efficiency of 79.4%.The polarization extinction ratio(PER) at all operational wavelengths was measured to be over 21 d B. To the best of our knowledge, this is the first report on a hundred-watt level linearly-polarized tunable Raman fiber laser.     

Investigation on achieving the diode-pumped weak line laser at 1.3 μm

In this paper, a continuous-wave (CW) diode-side-pumped Nd:YAlO₃ (Nd:YAP) laser operating at the weak line of 1339 nm has been achieved and investigated. The output of the 1339 nm laser was realized based on the polarization selection and reasonable transmittance design. The relationship between the output powers and resonator lengths of the 1339 nm Nd:YAP laser has been studied and the optimum resonator length was adopted to improve the output power. As high as 31.3 W output power of the a-axis polarized 1339 nm laser has been obtained at the pumping power of 555 W with the optical-optical and slope efficiencies to be 5.6% and 13%, respectively. This work will provide an effective way to obtain the weak line lasers for potential applications in spectroscopy, coherent terahertz generation, etc.     

93.7 W 1112 nm diode-side-pumped CW Nd:YAG laser

We demonstrate a high power continuous wave (CW) infrared laser operated at 1112 nm from a diode side-pumped Nd:YAG crystal with a plano-plano symmetrical resonator. By inserting an etalon, an output power of as high as 93.7 W at 1112 nm was obtained at the pump power of 570 W with conversion efficiency of 16.4%. The beam quality factor of M² was measured to be about 17. The wavelength tunable performance of the etalon was also analyzed. To the best of our knowledge, it is the highest output power at 1112 nm CW laser based on Nd:YAG crystal.     

High-efficiency eye-safe intracavity Raman laser at 1531 nm with SrWO4 crystal

A high-efficiency diode-end-pumped Q-switched eye-safe linearly-polarized intracavity Raman laser at 1531 nm is demonstrated, with Nd:YVO₄ as the laser medium and SrWO₄ as the Raman crystal. The highest average power of 1.93 W is achieved, with an incident pump of 15.6 W and a repetition rate of 35 kHz. The narrowest pulse duration of 4.9 ns and the highest peak power of 32.2 kW are obtained at a repetition rate of 5 kHz.     

KGW晶体外腔式高功率579nm喇曼黄光激光器

报道了579nm高功率KGd(WO4)2喇曼晶体外腔式喇曼黄光激光器的输出特性.基于808nm脉冲激光二极管侧面泵浦Nd∶YAG陶瓷、腔内BBO电光晶体同步延迟调Q和Ⅰ类临界相位匹配的LBO晶体腔外倍频方案,并通过外腔式KGW晶体Ng轴二阶斯托克斯喇曼频移,获得了579.54nm黄光激光输出.当脉冲信号重复频率为1kHz、532nm泵浦光最高平均功率为5.02W、脉冲宽度为10.1ns时,获得了最高平均功率2.58 W、脉冲宽度7.4ns、峰值功率348.6kW的579.54nm二阶斯托克斯喇曼黄光激光输出;532nm至579.54nm的光-光转化效率为51.4%、斜率效率为54.8%,光束质量因子Mx2-579.54=5.829、My2-579.54=6.336,输出功率不稳定性小于±2.35%.实验表明:外腔式喇曼结构能够高效地获得喇曼黄光,具有很高的光-光转化效率及良好的功率稳定性,并通过脉冲LD结合同步延迟电光调Q可获得高重复频率、高平均功率、窄脉冲宽度和高峰值功率的黄光激光输出.     

Modeling and experimental study of 780–808-nm AlGaAs/GaAs injection lasers with electron superlattice barriers

Electron superlattice barriers (ESBs) were used in AlGaAs/GaAs injection lasers to improve the electron confinement of the active layer by Bragg reflection of electron waves. The design of a separate-confinement heterostructure (SCH) laser with ESBs operating at 780–808 nm was optimized. Conventional SCH and SCH-ESB were prepared by low-pressure MOCVD epitaxy. Oxide stripe lasers with stripe widths of 100 and 200µm were prepared. The threshold current density of 0.3 kA/cm² and the characteristic temperature constantT ₀=220 K were measured at a wavelength of 808 nm for SCH-ESB lasers with an active-layer thickness of 40 nm and a resonator length of 0.4–0.5 mm. For conventional SCH lasers with the same geometry, a threshold current density of 0.42 kA/cm² andT ₀=160 K were obtained. Experimental results on the low-temperature photoluminescence characterizing ESB regions are presented and are compared with the calculated miniband energy spectrum of the superlattice structure. The leakage currents for ordinary SCH and SCH-ESB lasers were analyzed. Experimental verification of a reduction in the leakage current for SCH-ESB lasers was obtained.     

6.2 W laser-diode end-pumped continuous-wave Nd:YALO3 laser at 1.34 μm

We report a compact and efficient LD end-pumped linearly polarized Nd:YAP laser operating at 1.34 μm. The laser system with different crystal lengths, output couplers and cavity types were compared. Based on optimizing of the pump system and laser cavity, 6.2 W laser radiation at 1341.4 nm with c-axis polarized was achieved, corresponding to an optical conversion efficiency of about 24.8% with respect to the incident pump power. The laser threshold was only about 1.3 W and the optical slope efficiency was up to 27.2%.     

1.5kW全光纤线偏振激光器

报道了一台全光纤结构的1.5kW线偏振光纤激光器。激光器采用振荡器结合一级放大的主振荡功率放大器(MOPA)方案。振荡器中心波长为1080nm,工作时输出功率30 W,经放大器一级放大后实现近衍射极限输出,功率达到1.5kW,光-光效率81.5%,消光比13.8dB。这是目前线偏振光纤激光器输出功率的最高值。     

Quasi-three-level laser operation of Nd:Y<Subscript>0.53</Subscript>Gd<Subscript>0.47</Subscript>VO<Subscript>4</Subscript> mixed vanadate crystal oscillating at 913 nm

Efficient continuous-wave (CW) laser operation on the ⁴ F _3/2 → ⁴ I _9/2 transition of Nd:Y_0.53Gd_0.47VO₄, a mixed vanadate crystal, is demonstrated at room temperature employing a compact plano-concave resonator, generating a polarized output power of 0.39 W at 913.2 nm with 2.85 W of pump power absorbed, the optical-to-optical and slope efficiencies being 14 and 25%, respectively.