报道一种新型光纤化宽带可调连续波中红外激光器系统,该激光系统采用准相位匹配(QPM)的差频产生(DFG)技术,非线性晶体为多周期的周期性极化掺镁铌酸锂晶体(PPMgLN),掺镱光纤激光器(YDFL)用作抽运光源,可调激光器经掺铒光纤放大器(EDFA)功率提升后作为信号光源。利用建立的准相位匹配差频产生系统,获得了连续波中红外差频光输出;实验发现,温度导致相位失谐的半峰全宽(FWHM)为4.5 ℃;通过优化选择晶体周期,并结合调节信号光波长和控制温度,该准相位匹配差频产生系统可在3.1～3.6 μm内连续调谐。

A novel fiber-type widely tunable continuous-wave Mid-IR laser source was present and demonstrated. The Mid-IR laser system was based on the difference-frequency generation (DFG) and the quasi-phase-matched (QPM) techniques. The nonlinear crystal used is a periodically poled MgO-doped LiNbO3 (PPMgLN) crystal with multiple-periods structure. An ytterbium-doped fiber laser and a tunable laser cascaded with an erbium-doped fiber amplifier (EDFA) were used as the pump and the signal sources for the DFG process, respectively. With such a fiber-type QPM-DFG system, the continuous-wave Mid-IR radiation was obtained. It was found that the FWHM of the phase mismatching due to the temperature was about 4.5 ℃. By suitable choosing the crystal period combined with controlling the temperature and the wavelength of signal, Mid-IR radiation with continuously tuning range between 3.1 to 3.6 μm has been achieved with the system.