Ghosh Anirban, Yadav Deepika, Samanta G K
Opt Lett. 2019 Jul 15;44(14):3522-3525. doi: 10.1364/OL.44.003522.
We report on a compact and simple ultrafast source producing tunable radiation in the near-IR wavelength range. Based on single-pass frequency doubling of an ultrafast Cr:ZnS laser at 2360 nm with pulse width of 43 fs at a repetition rate of 80 MHz in MgO:PPLN crystal, the source produces maximum average output power of ∼2.43 W tunable across 1137-1200 nm with a maximum single-pass conversion efficiency as high as 65%. Without use of any pulse compression technique, the source produces output pulses in Gaussian shape with measured pulse width of ∼60 fs and spectral width of 39 nm centered at 1180 nm corresponding to a time-bandwidth product of 0.5. The output beam has a Gaussian spatial profile with measured M<1.32 and a peak-to-peak power fluctuation of 3% over 2 h. Using MgO:PPLN crystal of two different lengths, 1 mm and 2 mm, we have observed that the optimum second-harmonic generation efficiency of an ultrafast pulse laser, even in the presence of temporal walk-off, appears in the low pump focusing condition.
我们报道了一种紧凑且简单的超快光源，它能在近红外波长范围内产生可调谐辐射。基于在MgO:PPLN晶体中对波长为2360 nm、脉宽为43 fs、重复频率为80 MHz的超快Cr:ZnS激光进行单程倍频，该光源产生的最大平均输出功率约为2.43 W，在1137 - 1200 nm范围内可调谐，最大单程转换效率高达65%。在不使用任何脉冲压缩技术的情况下，该光源产生高斯形状的输出脉冲，测得的脉宽约为60 fs，光谱宽度为39 nm，中心波长为1180 nm，对应的时间带宽积为0.5。输出光束具有高斯空间分布，测得的M<1.32，并且在2小时内峰峰值功率波动为3%。使用1 mm和2 mm两种不同长度的MgO:PPLN晶体，我们观察到即使存在时间走离，超快脉冲激光的最佳二次谐波产生效率也出现在低泵浦聚焦条件下。
