物理学报2016，Vol.65Issue(15)：154205-1-154205-7,7.DOI:10.7498/aps.65.154205
885 nm双端泵准连续微秒脉冲1319 nm三镜环形腔激光∗
A quasi-continuous dual-end 885 nm dio de-pump ed three-mirror ring-cavity laser op erating at 1319 nm
摘要
Abstract
The 1319 nm lasers have important applications in the fields of optical fiber communication, laser medical treatment and laser color display. The Nd:YAG laser pumped by 808 nm laser diode is an efficient alternative to achieving 1319 nm laser output. In recent years, direct pump technology using 885 nm laser diodes has become more promising due to the dramatically reduced thermal effect and improved optical conversion efficiency. Quasi-continuous sodium beacon laser with microsecond pulse duration generated by the sum-frequency of 1319 nm and 1064 nm lasers can provide a gatable pulse format to eliminate the interference of atmospheric Rayleigh scattering and mitigate the spot elongation of sodium guide star to improve imaging accuracy. However, relaxation oscillation in the microsecond pulse could cause the damage to the nonlinear crystal and reduce the efficiency of sum-frequency generation. It is effective to suppress the relaxation by taking advantage of second harmonic generation, in which a nonlinear crystal is utilized to reduce the pulse peaks with higher intensity. <br> In this paper, we demonstrate a high-power relaxation-oscillation-free quasi-continuous microsecond pulse 1319 nm laser by using the dual-end 885 nmdiode-pumped three-mirror ring-cavity. Intra-cavity etalon and customized mirror coating are employed to prevent the 1064 nm and 1338 nmline of Nd:YAG laser crystal from oscillating. A power tuning device, including a thin-film polarizer and a halfwave plate is implemented as the output mirror of ring cavity, which enables continuous adjustment of the out coupling ratio. The output power of the 1319 nm polarized laser is 22.5 W pumped by 150 W 885 nm laser diode. The repetition rate is 800 Hz and pulse width is 150 µs. The corresponding optical conversion efficiency is 15%. The beam quality factor M 2 is measured to be M 2x =1.35 and M 2y =1.24. <br> By precisely adjusting the temperature of etalon viz. adjusting refractive index as well as thickness of the etalon material, laser wavelength is tuned from 1318.888 nm to 1319.358 nm, corresponding to a tunable range of 470 pm and tuning accuracy of 0.7 pm. A 1319 nm frequency doubling crystal KTiOPO4 (5 mm × 5 mm × 15 mm, θ =59.8◦ andϕ=0◦) is inserted into the cavity to suppress the relaxation oscillation. The pulse waveform quickly reaches a smooth regime, followed by a pulse spike at the initial stage and the loss of laser output power is only 1%. It is proved that it can be efficiently suppressed by inserting a frequency doubling crystal with negligible power loss. In conclusion, this paper provides a practical and effective technical means for achieving the high-power relaxation-oscillation-free quasi-continuous 1319 nm laser with microsecond pulse duration.关键词
885 nm双端泵/环形腔/弛豫振荡/波长调谐Key words
885 nm dual-end pump/ring cavity/relaxation oscillation/tunable wavelength引用本文复制引用
谢仕永,张小富,乐小云,杨程亮,薄勇,王鹏远,许祖彦..885 nm双端泵准连续微秒脉冲1319 nm三镜环形腔激光∗[J].物理学报,2016,65(15):154205-1-154205-7,7.基金项目
应用光学国家重点实验室开放基金、国家自然科学基金(批准号:61205101)和深圳市科技计划项目(批准号:GJHZ20140417113430592, JCYJ20140417113130693, JCYJ20150925163313898)资助的课题 （批准号:61205101）
