1.2 W中红外ZnGeP2光参量振荡器

报导了利用Tm,HoGdVO4激光器抽运双谐振ZnGeP2光参量振荡器实验研究.Tm(5%),Ho(0.5%)GdVO4晶体采用液氮制冷方式,工作在77 K温度条件下.以25 W波长为800 nm的光纤耦合激光二极管抽运,2 μm激光最大平均功率7 W,脉冲宽度小于30 ns, 脉冲重复频率5 kHz到20 kHz可调.非线性频率转换晶体ZnGeP2长15 mm,55?切割,OPO谐振腔为平平腔,腔长约25 mm.在5W的2 μm激光抽运下,脉冲重复频率10 kHz,实现了信号光3.7 μm及闲频光4.5 μm中红外激光输出,参量光脉冲宽度为15～17 ns,最大平均功率大于1.2 W,光-光转换效率为20%.测量参量光输出光束全宽度远场发散角4 mrad,光束质量M2因子小于3.     

Comparative investigation of long-wave infrared generation based on ZnGeP2 and CdSe optical parametric oscillators

Long-wave infrared(IR) generation based on type-II(o→e+o) phase matching ZnGeP 2(ZGP) and CdSe optical parametric oscillators(OPOs) pumped by a 2.05 μm Tm,Ho:GdVO 4 laser is reported.The comparisons of the birefringent walk-off effect and the oscillation threshold between ZGP and CdSe OPOs are performed theoretically and experimentally.For the ZGP OPO,up to 419 mW output at 8.04 μm is obtained at the 8 kHz pump pulse repetition frequency(PRF) with a slope efficiency of 7.6%.This ZGP OPO can be continuously tuned from 7.8 to 8.5 μm.For the CdSe OPO,we demonstrate a 64 mW output at 8.9 μm with a single crystal 28 mm in length.     

A ring ZnGeP2 optical parametric oscillator pumped by a Ho:LuAG laser

We have demonstrated that we believe to be the first ring ZnGeP₂ (ZGP) optical parametric oscillator (OPO) pumped by a pulsed Ho:LuAG laser. The maximum output power of the ring ZGP OPO laser was 5.51 W at 13.1 W incident Ho pump power, corresponding to a slope efficiency of 59.0 %. The ZGP OPO laser produced 14 ns mid-infrared pulses in the 3.72–4.01 and 4.37–4.75 μm spectral regions simultaneously. In addition, the continuous wave Ho:LuAG laser generated 26.5 W of linearly output at 2,094.4 nm at the absorbed Tm pump power of 49.9 W.     

High-power,high-quality ZGP OPO pumped by a Tm,Ho:GdVO<Subscript>4</Subscript> laser

We report a ZGP OPO system capable of producing >6 W at a signal wavelength of 3.80 μm and an idler wavelength of 4.45 μm. The pumping source is the Tm,Ho:GdVO₄ laser operated at 2.049 μm with an M ² of 1.07. The ZGP OPO generated a total combined output power of 6.1 W at signal wavelength and idler wavelength under pumping power of 18.3 W, and an M ² of 1.7 for OPO output was obtained.     

A High-Power,Long-Wavelength Infrared ZnGeP<Subscript>2</Subscript> Opo Pumped by a <Emphasis Type="Italic">Q</Emphasis>-Switched Tm,Ho:GdVO<Subscript>4</Subscript> Laser

We report a high-power, long-wavelength infrared ZnGeP₂ (ZGP) optical parametric oscillator (OPO) pumped by a Q-switched Tm,Ho:GdVO₄ laser. The wavelength tuning range of 7.8–9.9 μm is realized by rotating the external angle of the ZGP crystal. We obtain an output power over 30 mW across the whole wavelength range and achieve a 1.71 W output power at 8.08 μm by transmitting the OPO parameters, corresponding to an idler laser slope efficiency of 12.1%.     

Comparative investigation of long-wave infrared generation based on ZnGeP2 and CdSe optical parametric oscillators

Long-wave infrared (IR) generation based on type-II (o→e+o) phase matching ZnGeP₂ (ZGP) and CdSe optical parametric oscillators (OPOs) pumped by a 2.05 μm Tm,Ho:GdVO₄ laser is reported. The comparisons of the birefringent walk-off effect and the oscillation threshold between ZGP and CdSe OPOs are performed theoretically and experimentally. For the ZGP OPO, up to 419 mW output at 8.04 μm is obtained at the 8 kHz pump pulse repetition frequency (PRF) with a slope efficiency of 7.6%. This ZGP OPO can be continuously tuned from 7.8 to 8.5 μm. For the CdSe OPO, we demonstrate a 64 mW output at 8.9 μm with a single crystal 28 mm in length.     

LD pumped 2-μm CW laser from Tm,Ho:GdVO4

A set of fiber-coupled continuous wave (CW) diode lasers has been used to pump Tm, Ho:GdVO4 and generate 2.048-μm laser radiation at liquid nitrogen temperature. The optical-optical efficiencies of 25%,output power of 3.5 W, and pumping threshold of 838 mW have been obtained and compared with those from Tm, Ho:YLF under identical experimental conditions.     

激光二极管抽运(Tm,Ho)∶YLF激光器光谱特性实验分析

Ho∶YLF晶体的5I7和5I8斯塔克能级分裂数较多,形成2047~2070nm宽的增益谱带,对于可调谐2μm激光及宽带激光放大器研究具有重要意义。理论上分析了(Tm,Ho)∶YLF晶体的能级结构,并对晶体掺杂浓度和长度进行了优化。实验研究了激光二极管抽运微片Tm(原子数分数0.06),Ho(原子数分数0.004)∶YLF激光谱线可调谐特性,调谐范围2.0656~2.0671μm。利用(Tm,Ho)∶YLF晶体的宽增益谱特性,将其作为激光二极管抽运激光放大器,成功地将2.048μm(Tm,Ho)∶GdVO4激光功率放大了2.5倍。实验上测量了(Tm,Ho)∶YLF晶体在强抽运条件下480~492nm及530~550nm可见波段的上转换蓝绿光荧光谱。     

8.30 μm singly resonant ZnGeP2 optical parametric oscillators pumped by a Tm,Ho:GdVO4 laser

A single resonator 8.30 μm ZnGeP₂ (ZGP) optical parametric oscillators (OPO) was reported in the paper. The OPO was pumped by a 10.2-W Tm,Ho:GdVO₄ laser at 8 kHz in a Q-switch mode, a 170-mW idler was obtained at 8.30 μm, and the output power of the idler and signal wave was 1.0 W, corresponding to an optical-optical conversion efficiency of 10.3% and a slope efficiency of 20.9%. Tm,Ho:GdVO₄ laser was pumped by a 30-W fiber-coupled laser diode (LD) at the center wavelength of 801 nm. The output wavelength of Tm,Ho:GdVO₄ laser was at 2.05 μm, and the energy per pulse of 1.28 mJ in 18 ns was achieved at 8 kHz with the peak power of 71.1 kW.     

光纤耦合二极管端泵2 μm CW双掺)Tm,Ho∶GdVO4激光器

同YLF和YAG 基质相比,在Tm-Ho∶GdVO₄晶体中Tm³⁺离子在800 nm附近有非常强的和宽的吸收带,所以该晶体非常适合商品化的GaAlAs激光二极管泵浦.在液氮制冷晶体条件下,利用光纤耦合激光二极管及消色差光学耦合系统端面泵浦双掺5％Tm,0.5％Ho∶GdVO₄晶体,在泵浦功率14 W、泵浦波长794 nm时,实现了2.048 μm激光输出,连续运转输出功率3.6 W,相应的光光转换效率为25.7％,斜率效率26.6%.相对于吸收的泵浦功率,光光转换效率为35%.由于Tm³⁺离子间的交叉弛豫效应,泵浦量子效率达到1.3.     

3.6-W cryogenic Tm,Ho:YLF laser pumped by fiber-coupled diodes module

In this paper, we report a high power cryogenic cooling Tm(6 at.-%),Ho(0.5 at.-%):YLF laser end-pumped by a 19-fiber-coupled-diodes module with the central wavelength of 792 nm at 20°. The highest continuouswave power of 3.6 W at 2.051 μm is attained under pumping power of 13.6 W, corresponding to opticaloptical conversion efficiency of 26%, and the slope efficiency is larger than 30%. The threshold power is only about 0.16 W because of the long lifetime, large effective emission cross section, and low re-absorption in Tm,Ho:YLF crystal.     

激光二极管抽运（Tm，Ho）：YLF微片激光器的实验研究

从理论上分析了准三能级(Tm，Ho)：YLF晶体的增益与温度关系，晶体温度的降低和长度的缩短有利于减小重吸收损耗对激光器运行性能的影响。在室温条件下，用2．7w波长为792nm激光二极管端面抽运Tm(原子数分数0．06)，Ho(原子数分数0．004．)：YLF微片激光器，阈值抽运功率为450W，当入射到晶体内的激光二极管功率为1．88W时，2μm激光最大输出功率为328mW，斜率效率为22．5％，光—光转换效率达17．4％。为达到激光最佳运行条件，还探讨了激光二极管波长，抽运光偏振方向以及晶体温度对Tm，Ho激光器性能的影响。     

二极管泵浦的2 μm高重复频率脉冲固体激光器

 报道了连续二极管端面泵浦2 μm高重复频率Tm,Ho:YLF激光器的实验研究结果。792 nm光纤耦合激光二极管作泵浦源,泵浦液氮制冷的Tm,Ho:YLF晶体。动态运转时,平均输出功率达到4 W,相应的能量抽取效率大于85%。采用声光调Q方式,重复频率1～50 kHz可调,10 kHz时,峰值功率达到12 kW,最小脉宽为32 ns。同时,还对二极管泵浦2 μm激光器设计中的各种因素进行了分析。     

Mid-infrared optical parametric oscillator based on ZnGeP2 pumped by 2-μm laser

We present a 3 5 μ m optical parametric oscillator (OPO) based on ZGP pumped by KTP OPO 2.1-μ m laser. The tuning curves of ZGP OPO are calculated. The 8 ×6 ×18 (mm) ZGP crystal, whose end faces are antireflection coated at 2.1 and 3.7 4.6 μ m, is cut as θ =53.5°, φ =0°. When the pump power of 2.1-μ m polarized laser is 15 W at 8 kHz, 5.7-W output power and 46.6% slope efficiency are obtained with a ZGP type I phase match. Central wavelengths of the signal and idler lasers are 4.10 and 4.32 μ m, respectively. Pulse duration is about 27 ns. Beam quality factor M 2 is better than 1.8. The tunability of 3 5 μ m can be achieved by changing the angle of the ZGP crystal.     

Effect of resonator length on ZnGeP<Subscript>2</Subscript> doubly resonant optical parametric oscillator pumped by a Tm,Ho:GdVO<Subscript>4</Subscript> laser

The effect of resonator length on ZnGeP₂ doubly resonant optical parametric oscillator was reported in this letter. With the employment of a Tm,Ho:GdVO₄ laser as the pump source at 2.05 μm, we have found that there are obvious peaks of the output power when the resonator lengths are matched to the length of the pump source. The ZGP OPO can generate a maximum output power of 4.27 W at 3.80 μm signal and 4.45 μm idler when the resonator length matches that of the pump source.     

1.57μm被动调Q光学参量振荡器

在半导体泵浦被动调QNd∶GdVO4/Cr4+∶YAG激光腔内,利用KTP晶体实现了高重复频率的内腔OPO的稳定运转。OPO其信号光转换效率为7%,斜效率为10.3%。当泵浦功率7.3W时,可获得平均功率为0.48W,重频15kHz,脉宽6ns,峰值功率达13KW的1570nm激光输出。     

Room temperature efficient continuous wave and Q-switched operation of a Ho:YAP laser

We report the continuous wave and acousto-optically Q-switched operation of a Tm:YLF-pumped Ho:YAP laser at room temperature. Continuous wave output power of 6.8 W at 2118 nm was obtained under the incident pump power of 13.4 W, corresponding to a slope efficiency of 65.6% and a conversion efficiency of 50.7%. For the Q-switched mode, a maximum pulse energy of 1.28 mJ and a minimum pulse width of 31 ns at the repetition rate of 5 kHz were achieved, resulting in a peak power of 41.3 kW. In addition, the Ho:YAP laser was employed as a pumping source of ZGP optical parametric oscillator, the total average output power of which was 3.2 W at 4.08 and 4.41 μm with a slope efficiency of 69.5%, corresponding to the diode-to-mid-IR conversion efficiency of 9.0%.     

A compact high efficient diode-double-passing-pumped mid-IR Tm:YLF laser at room temperature

A new compact high efficient diode-double-passing-pumped Tm:YLF laser at room temperature is presented. Using a crystal of 3 mm × 3 mm × 12 mm 4% doping Tm:YLF and double-end-double-passing pumping cavity structure without complex optical splitter pumping system, 5.6 W CW 1907.6 nm laser is obtained at 26.2 W 792 nm pumping laser. The slope efficiency is as high as 37.8% and the spectrum width is 2 nm. The relationship between cavity length and output laser is also analyzed. Experiments verify that the highest energy and convertion efficiency can be reached by optimizing the oscillator cavity length. Finally, we used this Tm:YLF laser to pump Ho:YAG crystal at room temperature and achieved 1.65 W 2.1 μm output laser with slope efficiency 67%.     

磷锗锌光学参量振荡器技术研究

 报道了一台高重复频率2 mm光学参量振荡器泵浦的磷锗锌光学参量振荡器。磷锗锌晶体(ZnGeP₂，简称ZGP)采用Ⅰ类相位匹配方式，切割角度q为55°，f为0°，尺寸5.5 mm×6 mm×18 mm，在4.0 kHz重复频率下，当注入5.2 W的2 mm圆偏振光时，获得310 mW中红外输出，p偏振态2 mm到3～5 mm光-光转换效率12%。通过调节晶体的角度，实验获得ZGP光学参量振荡器的波长调谐曲线，在误差范围内与理论变化规律相符。     

An Ho:YAG Laser with Double-Pass Pumping and the ZnGeP2 OPO Pumped by the Ho:YAG Laser

We report an efficient Ho:YAG laser end pumped by Tm:YLF lasers with double-pass pumping. We achieve the maximum continuous wave (CW) output power of 46.0 W with a single-pass pumping and 50.2 W with a double-pass pumping, corresponding to a slope efficiency of 58.0% and 62.8%, respectively. In addition, we use the Ho:YAG laser as a pumping source of the ZnGeP₃ optical parametric oscillator (OPO) and obtain the maximum average output power of 14.2 W with a linear cavity and 17.0 W with a ring resonator, respectively.