为了获得高效率、小型化、稳定性好的激光器,种子激光器由激光二极管抽运Tm,Ho:YLF微片获得单模输出。短腔的自由光谱区比较宽,易于选单纵模,微片厚度0.9 mm,两端镀膜,构成微型谐振腔。微片置于杜瓦瓶中,采用液氮制冷的方式,在低温下工作,增加了输出激光的稳定性。利用光纤延时自拍法进行频率短期稳定度测量,得到单模激光器短期稳定度为2.6 kHz/μs,利用示波器估测长期稳定度小于35 MHz。获得2.067 μm的单模输出,线宽小于40 MHz。利用刀口法测量得到光束质量为1.082,最大单模输出功率为32.8 mW,斜率效率达到25.2%,光-光转换效率达23.8%,功率输出不稳定性小于1%。

To attain high efficiency, miniature and stable laser, we take Tm,Ho:YLF(Tm 6%;Ho 0.4%) microchip pumped by diode laser as the seed laser. Short resonant cavity which owns broad free spectral range is useful to select single-frequency. The microchip is 0.9 mm. Both end faces are coated. The microchip itself is the oscillate cavity. It is placed in the Dewar bottle. The bottle is filled with liquid nitrogen to keep the temperature at 77 K, which enhances the stability of output power. Self-beat of fiber delay method is used to measure the short-term frequency stability. It indicates that the short term stability is about 2.6 kHz/μs. And by using the oscilloscope, the long term stability is estimated at 35 MHz. Single-mode output laser with the wavelength of 2.067 μm is obtained, and its bandwidth is less than 40 MHz. The beam quality is about 1.082 which is measured by the knife-edge method. The maximal output power is up to 32.8 mW. The slope efficiency is 25.2%, and the optical-optical efficiency is 23.8%. The instability of the output power is less than 1%.