纳秒声光调Q光纤激光器产生超连续谱

Generation of supercontinuum spectra from acousto-optic Q-switched nanosecond fiber lasers

根据现有生成超连续谱方案的不足,搭建了一台全光纤结构的纳秒声光调Q激光器。该激光器中心波长为1 064.3nm,重复频率为20kHz,脉冲宽度为250ns；经过一级放大得到的输出功率为13.02 W。将信号光耦合进自行研制的高功率模场适配器（MFA）,得到了10.7 W的信号光输出,耦合效率高达82.2%。将MFA与光子晶体光纤（PCF）熔接,得到了平均功率为5.43 W的超连续谱输出,光谱覆盖为900～1 700nm。由于实验采用的声光调制器（AOM）脉宽较宽,导致泵浦光峰值较低,非线性效应较弱,未能使超连续谱向可见光展宽。因此,建议采用较窄脉宽的AOM作为调Q元件来实现高峰值功率输出,以改善纳秒脉冲PCF产生的超连续谱特性。

For the shortcomings of current schemes to generate laser supercontinuum spectra,an acousto-optic Q-switched nanosecond all fiber laser is established.The laser shows its central wavelength at 1 064.3nm,repetition rate of 20kHz and a pulse duration of 250ns.After primary amplification,the output power is 13.02 W.When the amplified pulse is launched into a self-made high power Mode Field Adaptor（MFA）,the signal light output can be 10.7 W and the coupling efficiency is up to 82.2%.After the MFA is spliced with a piece of Photonic Crystal Fiber（PCF）,the output supercontinuum spectrum with an average output power of 5.43Wcan be obtained at a wavelength range from 900nm to 1 700nm.As the Acoustic Optical Modulator（AOM）in the experiment has a wider pulse duration,which leads to a lower peak value of pump light and a lower nonlinear effect,so that the supercontinuum spectra do not include the visual part.It suggests that the AOM with narrower pulse duration should be used to generate high peak power to widen the spectral bandwidth and flatten the supercontinuum spectra.