基于光纤激光器的中红外差频多波长激光产生

Mid-IR multiwavelength difference frequency generation laser source based on fiber lasers

针对由YDFL和EDFL作为基频光源的QPM-DFG激光系统,利用PPMgLN晶体的色散关系及其温度特性,有效拓宽了QPM波长接受带宽.模拟结果表明,当采用1550和1060nm波段的EDFL和YDFL分别作为DFG的信号和抽运光源时,对于相同的中红外波段,满足QPM条件所允许的抽运光波长变化范围远大于信号光波长变化范围.当固定信号光波长为1560nm时,对于给定的晶体温度,1060nm波段抽运光的QPM接受带宽超过17nm,对应于中红外差频光带宽可约180nm.采用多波长YDFL作为抽运源,单波长EDFL后接EDFA作为信号源,在保持PPMgLN晶体温度和极化周期73.5℃和30μm不变的前提下,实验获得了波长间隔为14nm的14个中红外激光波长的同时输出,并且,改变信号光波长,可实现对这种中红外多波长激光的同步调谐.

The quasi-phase-matched （QPM） wavelength acceptation bandwidth for a difference frequency generation （DFG） mid-IR laser source with fiber lasers as the fundamental sources is effectively broadened by using the dispersion relations and its temperature characteristic of periodically poled MgO-doped LiNbO3 （PPMgLN）.Our simulation results show that,with an erbium-doped fiber laser （EDFL） and a ytterbium-doped fiber laser （YDFL） respectively operating near 1550 and 1060 nm wave-bands as the signal source and pump source,for the same mid-IR wavelength regions,the allowable wavelength range given by the QPM condition for the pump wave is much larger than that for the signal wave.When the wavelength of the signal wave is fixed at 1560 nm,for a given optimized crystal temperature,the acceptance bandwidth for the pump wave is over 17 nm,corresponding to the acceptance bandwidth for the idler wave of about 180 nm.Based on it,by using a multiwavelength YDFL and a single wavelength EDFL cascaded by an erbium-doped fiber amplifier （EDFA） respectively as the pump source and the signal source,14-wavelength mid-IR laser lines,with a spacing of about 14 nm in between,are obtained simultaneously with our QPM-DFG laser system when both the temperature and the grating period of the PPMgLN used being kept unchanged at 73.5 ℃ and 30 μm respectively.Moreover,the mid-IR multiwavelength laser lines may be tuned synchronously by varying the signal wavelength.