基于LBO的高功率飞秒绿光抽运的光学参量振荡器

High Power Femtosecond Green-Pumped Optical Parametric Oscillator Based on Lithium Triborate

三硼酸锂（LBO）具有良好的非线性光学特性和极其稳定的物化性能,其色散量对晶体温度变化敏感,是可实现非临界相位匹配的优良的非线性光学晶体。报道了高功率绿光飞秒激光同步抽运以三硼酸锂（LBO）为非线性晶体的单共振光学参量振荡器（OPO）。抽运源为高平均功率大模场面积掺镱光子晶体光纤飞秒激光器放大级的输出飞秒光的锁模倍频激光,通过调节晶体温度,采用非临界相位匹配方式,获得了红光至近红外光可调谐的高功率飞秒激光,OPO的信号光调谐范围为670~880nm,相应闲频光在2320~1270nm范围内可调。在3.4W抽运功率下,中心波长为694nm的信号光输出获得最高平均功率为660mW,脉冲宽度为132fs,转换效率为19.4%。

Lithium triborate （LBO） possesses desirable nonlinear optical characters, as well as stable chemical and mechanical properties. Its dispersion is sensitive to the change of the crystal temperature, which allows this nonlinear optical crystal to be used to achieve noncritical phase matching. This paper demonstrates a femtosecond synchronous green-pumped singly resonant optical parametric oscillator （OPO） based on lithium triborate. As the pump source, a frequency-doubled mode-locked Yb-fiber laser-amplifier system is used, which can produce femtosecond laser with high average power and large mode field area. By adjusting crystal temperature, tunable high power femtosecond laser can be obtained from red to near infrared using noncritical phase matching method. The signal pulses of the optical parametric oscillator have a wide spectral tuning range of 670~880 nm and idler pulses are tunable in the range of 2320~1270 nm. At a pump power of 3.4 W, the output highest average power of 660 mW at 694 nm central wavelength is achieved with the pulse duration of 132 fs and the slope efficiency of 19.4%.