LD纵向泵浦腔内倍频激光器腔参数的选择

从理论上研究了在一定长ＫＴＰ情况下ＬＤ纵向泵浦Ｎｄ：ＹＶＯ４／ＫＴＰ腔内倍频激光器的绿光输出与腔长、输出镜曲率半径及泵浦光斑半径等参数的关系。根据分析选择了一组实验参数，在入射泵浦功率为６６８．７ｍｗ时获得了１５３．９ｍｗ的绿光输出，光一光转换效率为２３％。将实验结果与理论计算值进行了比较，两者符合较好。     

Observation of both second-harmonic and multiphoton-absorption-induced luminescence in ZnO

The confusion over second-harmonic generation (SHG) and multiphoton-absorption (MPA)-induced luminescence in ZnO is observed under excitation with femtosecond laser between 800 and 1000 nm at room temperature. Excitation power dependence measurements show SHG is a two-photon process, and MPA is a three- or four-photon process. These are confirmed with interferometric pulse autocorrelation experiments. Excitation power density is a main regulatory factor for this confusion.     

蓝光抽运Pr∶KYF晶体及腔内倍频紫外激光技术

报道了一种蓝光(471nm)抽运的全固态Pr∶KYF激光器。其入射抽运激光阈值功率为0.4 W,当注入的抽运功率为2.5W时,得到了最大212mW的610nm波长的激光输出。然后采用I类临界相位匹配的β-BaB2O4(BBO)晶体进行内腔倍频,得到了最大11mW的二次谐波305nm紫外激光输出。通过刀口法可测量到在TEM00模式下,输出光束的质量因子M2=1.25;光-光转换效率达4.4%;输出功率在30min内的不稳定度优于4.3%。采用USB-4000型光谱仪检测到输出为305nm的激光光谱。     

40-GHz picosecond-pulse second-harmonic generation in an MgO-doped PPLN waveguide

Second-harmonic generation (SHG) of 40-GHz picosecond optical pulses with different pulsewidths, pulse energies, and central wavelengths in a MgO-doped periodically poled lithium niobate (PPLN) waveguide is studied experimentally and theoretically. In the experiments, the picosecond pulses are generated from a 40-GHz mode-locked fiber laser and two tunable filters, with which the lasing wavelength can be tuned from 1530 to 1570 nm, and the pulsewidth can be tuned from 2 to 7 ps. The second-harmonic (SH) pulses are generated when the picosecond pump pulses pass through the MgO-doped PPLN waveguide. Dependences of SHG on pump pulsewidth, average pump power, and pump central wavelength are then investigated systematically. Meanwhile, dynamic behaviors of both pump and SH pulses in propagation are simulated numerically. Based on the temporal and spectral characteristics of SHG, a quantitative and systematic analysis on SHG efficiencies in terms of both pulse energy and spectral peak is presented. The simulation results are in good agreement with the measured data.     

Study on the Pr:KYF ultraviolet laser at 305 nm pumped by blue laser

An all-solid-state Pr:KY3F10(Pr:KYF) laser pumped by blue laser(471 nm) has been demonstrated.With the incident pump power of 2.6 W,the maximum output power at 610 nm is 213 mW.Moreover,the intracavity second-harmonic generation(SHG) is also achieved with the maximum ultraviolet(UV) power at 305 nm of 11 mW by using a β-BaB2O4(BBO) nonlinear crystal.     

Thermal Management in 2.3- μm Semiconductor Disk Lasers: A Finite Element Analysis

Finite element analysis is used to study heat flow in a 2.3-mum semiconductor disk laser (or vertical-external-cavity surface-emitting laser) based on GalnAsSb-AlGaAsSb. An intra-cavity diamond heatspreader is shown to significantly improve thermal management-and hence power scalability-in this laser compared to the substrate thinning approach typically used in semiconductor disk lasers operating around 1 mum. The parameters affecting the performance of an intracavity heat-spreader are studied in the context of a 2.3-mum semiconductor disk laser: the thermal impedance at the interface between the semiconductor gain material and the heatspreader is found to be much more important than the mounting arrangements for the gain-heatspreader composite; power scaling with pump spot radius-increasing the pump power at constant pump intensity-is found to be intrinsically limited; and the pump wavelength is predicted to have less affect on thermal management than might be expected. Direct pumping of the quantum wells is found to significantly reduce the temperature rise per unit pump power.     

皮秒级高功率紫外可调谐激光

采用 35 5nm主被动锁模YAG激光器作抽运源 ,结合BBO晶体的倍频调谐特性 ,获得了 2 0 0～ 35 0nm的皮秒级紫外可调谐激光 ,转换效率为 15 3 %～ 2 3 6 %。对影响参量光倍频转换效率的发散角、线宽进行模拟和分析 ,其结果与实验吻合。     

A continuous tunable source of coherent UV radiation

We describe a continuous tunable ultraviolet radiation source, operating in the spectral range 290-315 nm by intracavity frequency doubling of a rhodamine 6G dye laser. Maximum intracavity second-harmonic power of 1.1 mW was obtained at 296 nm with a bandwidth of 0.1 nm.     

二极管泵浦Yb∶YAG准三能级1024 nm薄盘激光器

采用二极管泵浦Yb∶YAG晶体实现准三能级连续1024 nm薄盘激光器,1024 nm谱线是由Yb∶YAG晶体内的2F5/2-2F7/2能级跃迁实现的,实验中采用折叠腔结构。泵浦光16次通过Yb∶YAG晶体,当注入泵浦功率为17.9 W时,1024 nm激光输出功率为370 mW,通过采用I类临界位相匹配LiB3O5(LBO)晶体进行腔内二次谐波倍频,获得最大输出功率为45 mW的512 nm蓝-绿激光稳定输出,蓝-绿色激光30 min功率稳定度优于4.3%。     

0.8 W optically pumped vertical external cavity surface emitting laser operating CW at 1550 nm

An InP based optically pumped vertical external cavity surface emitting laser has been designed and optimised for emission at 1550 nm. To overcome thermal limitations an intra-cavity synthetic diamond heatspreader is bonded to the gain structure. The laser produces 780 mW at -30/spl deg/C and 100 mW at 20/spl deg/C in a near Gaussian beam (M/sup 2/<1.2).     

5-W Yellow Laser by Intracavity Frequency Doubling of High-Power Vertical-External-Cavity Surface-Emitting Laser

We report on the development of a high-power tunable yellow–orange laser. It is based on intracavity frequency doubling of a widely tunable, highly strained InGaAs–GaAs vertical-external-cavity surface-emitting laser operating near 1175 nm. Over 5 W of continuous-wave output power is achieved and is tunable over a 15-nm band centered at 587 nm. This compact low-cost high-power yellow–orange laser provides an innovative alternative for sodium guidestar lasers, medical and communication applications.      

A green laser at 517 nm based on intracavity frequency doubling of the diode-pumped Yb:LO laser

We report for the first time, to our knowledge, the diode-pumped continuous-wave （CW） thin-disk Yba＋-doped Lu203 （Yb：LO） laser at 1 034 nm and the second-harmonic generation at 517 nm. With a 6.3% output coupler, the maximum output power is 1.17 W under a pump power of 18.5 W. Moreover, the intracavity second-harmonic generation （SHG） is also -achieved with power of 193 mW at 517 nm by using an LiB305 （LBO） nonlinear crystal. The beam quality fac- tor M2 is about 1.28. The fluctuation of the output power is about 3% in 1 h.     

掺钕保偏光纤激光器腔内倍频实验研究

从双包层光纤激光器的速率方程和光传输方程出发,数值模拟得到泵浦功率20 W时最佳增益光纤长度。在此基础上,采用线型直腔结构,通过透镜耦合的方式,用808 nm半导体激光器对掺Nd3+熊猫型保偏双包层光纤进行端面泵浦,获得1060 nm连续偏振的基频光输出,其线宽小于5 nm,光-光转换效率达到50%;之后,采用腔内插入KTP晶体的方式对基频光进行倍频获得530 nm的绿光输出,其线宽小于3 nm,倍频效率达到20%。在20 W的入纤功率泵浦下,得到2 W的530 nm连续绿光输出。     

Synthetic Diamond for Intracavity Thermal Management in Compact Solid-State Lasers

The intracavity use of newly developed low-birefringence synthetic diamond for thermal management in compact solid-state lasers is examined both experimentally and theoretically. A comparison - using single-crystal natural diamond as a base line - is made between synthetic, single-crystal diamond types: chemical vapor deposition and high pressure/high temperature grown diamond. The synthetic diamond samples are shown to possess significantly lower birefringence than often occurs in natural single-crystal diamond while maintaining the excellent thermal management properties and low insertion loss of natural diamond. Low threshold, high efficiency laser operation is demonstrated in polarization sensitive cavities incorporating intracavity synthetic diamond using both doped-dielectric and semiconductor gain elements. In addition, finite element analysis is used to demonstrate the potential of diamond to reduce thermal distortion and stress in doped-dielectric disk lasers. A 15 W Nd:GdVO₄ disk laser utilizing diamond is demonstrated. These results highlight the potential of low birefringence synthetic diamond for intracavity thermal management applications in solid-state lasers.     

VRM腔高光束质量高功率双波长激光器

研制的双波长短脉冲激光器采用大模体积腔+渐变反射率输出镜技术,对二极管泵浦棒状激光介质产生的热透镜及热退偏进行补偿,在500 Hz下实现了谐振腔短脉冲能量140 mJ,脉宽约17.76 ns的1 064 nm激光输出,20 min能量不稳定性RMS值小于0.3%,激光光束质量M21.6。该实验结果与采用MOPA技术路线谐振腔+预放的方式技术指标相当,但采用谐振腔的技术路线结构简单紧凑。采用水热法生长抗灰迹效应的GTR-KTP晶体作为倍频晶体,相位匹配方式选择Ⅱ类相位匹配,倍频后532 nm激光单脉冲最高能量96 mJ,最高倍频效率68.6%,激光光束质量M22.1。通过能量调节设计,实现了线偏振态1 064 nm和532 nm激光功率连续可调共光轴输出。     

利用二次谐波产生研究Al2O3/Al(111)表面的动力学变化

主要介绍了当激光入射到单晶金属Al2O3／Al(111)表面时将发生二次谐波产生(SHG)现象的实验装置和实验方法,利用该装置可以研究SHG和从Al2O3／Al(111)表面反射的SHG在空间各向异性的变化情况,从而可以探测Al2O3／Al(111)表面结构对称性。实验中发现,当脉冲激光功率在2×106 W／cm2-9．6×106W／cm2范围内变化时,没有检测到SHG信号的各向异性变化;当使用P-极化泵浦激光时,发现Al2O3／Al(111)样品绕法线旋转360度时,P-极化的SHG信号在空间三个方向上呈现最大值相等;当使用脉冲强度为12×100 W／cm2的1064 nm P-极化泵浦激光时, Al2O3／Al(111)表面被损坏,损坏后的表面其SHG信号并不呈现对称的各向异性变化,当使用脉冲强度为11×106W／cm2的1064 nm P-极化泵浦激光时产生表面退火现象,从退火表面所产生的反射532 nm P-极化SHG信号中发现,SHG信号呈现衰减的各向异性成分。     

双光纤光栅法-珀腔可调谐窄线宽激光器

基于游标原理,利用一对自由谱宽(FSR)略有不同的光纤布喇格光栅法布里-珀罗腔(FBG-FP)作为模式选择器件,设计了一种新颖的环形腔光纤激光器。从理论和实验上研究了该激光器的特性。通过对可调谐FBG-FP应力调谐,在1552.240～1552.912 nm范围内,以96 pm为平均间距,获得了8个由固定FBG-FP的透射谱所确定的窄线宽稳定激光输出。8个输出波长的平均功率为-17.66 dBm,波动在0.7 dB范围内。当泵浦光的功率为95 mW的时候,输出信号的信噪比均大于50 dB。实验上每隔1 min用光谱分析仪(OSA)对输出光波长自动扫描,记录的输出光波长漂移在数皮米范围内,且功率的波动小于0.1 dB。这种可调谐的窄线宽光纤激光器在光纤通信和光纤传感方面有潜在的应用价值。     

Silver thiogallate (AgGaS2)--Part II: Linear optical properties

New measurements are presented on the absorption of silver thiogallate and related to fundamental mechanisms. All available data on the refractive indices of silver thiogallate, including new results for the visible, have been incorporated into sets of Sellmeier expressions. Different Sellmeier constants are given for visible and infrared wavelengths and also for crystals from different sources. Confirmation of some predictions from these Sellmeier expressions has been obtained by second-harmonic generation (SHG) experiments with a tunable optical parametric oscillator. Preliminary results on laser damage are summarized.     

High-power long-pulse second harmonic generation and optical damage with free-running Nd:YAG laser

Frequency doubling with a free-running long-pulse Nd:YAG laser and LBO or KTP nonlinear crystals yields conversion efficiency of up to 17.5% and 162 W peak power in the second harmonic. This efficiency is obtained for a TEM/sub 00/ beam with rectangular temporal pulse shape of 50 to 400 /spl mu/s. To our knowledge, this is the highest second-harmonic generation (SHG) efficiency reported for the long-pulse free-running configuration. The efficiency is limited by optical damage with much lower threshold than in the Q-switch domain. The damage is preceded by a saturation effect of the SHG efficiency. Both wavelengths (fundamental and second-harmonic) are necessary for the creation of the catastrophic damage. We present first evidence for a mechanism that involves creation of transient absorption centers by the second-harmonic radiation due to multiphoton absorption. Absorption of the fundamental wave at these centers leads to local heating and ultimately catastrophic damage.     

Tunable Fiber Laser Using a Broad-Band Fiber Mirror and a Tunable FBG as Laser-Cavity Ends

By using a broad-band fiber mirror (BFM) and a tunable fiber-Bragg-grating at either end of laser cavity, a wavelength tunable erbium-doped fiber laser is demonstrated. In a forward pump scheme using 100 mW pump power at 1480 nm, stable lasing output power of 21.14-mW measured at 1544.8 nm is obtained with a threshold pump power of 4.7 mW. A side-mode suppression ratio as high as 57.9 dB, wavelength tuning range up to 30 nm with step resolution of 0.2 nm and power variation less than plusmn1.0 dB are achieved. For a backward pump scheme, the BFM acts as a broad-band reflector both for the lasing signal and pump source. The high performance, cost-effective BFM based tunable fiber laser may play an important role in fiber optics communication and fiber sensing applications.