双包层光纤激光器和非线性光学材料(如周期性极化的铌酸锂晶体,PPLN)相结合,开辟了实用性非线性光学器件的一个新领域。研究了准相位匹配周期性极化反转铌酸锂晶体对宽带准连续光纤激光倍频的温度特性和频谱特性。在理论上,从准相位匹配相位失配关系出发,推导了晶体温度与抽运源中心波长的关系以及温度响应带宽,并和已报道实验结果进行了比较,二者符合得很好。此外,还推导了倍频周期极化铌酸锂晶体对抽运基频光源的响应谱线带宽。在实验上,采用长度20 mm,极化周期6.5 μm,厚度0.5 mm的周期极化铌酸锂晶体光纤激光器准连续宽带输出进行了倍频,获得了在不同控制温度下的倍频光光谱,并对此进行了详细分析。

Developments in double clad fiber lasers, coupled with engineered nonlinear optical materials such as periodically poled lithium niobate (PPLN), are opening a way for a whole new class of practical nonlinear optical devices. Temperature characteristic and spectra characteristic of second harmonic generaration (SHG) in PPLN using quasi-CW broad band fiber laser have been investigated. The central fundamental wavelength dependence of PPLN temperature and the temperature FWHM phase-matching bandwidth were theoretically studied. The fundamental wavelength FWHM phase-matching of PPLN was calculated too. The 20 mm long PPLN with 6.5 μm poling period and 0.5 mm thick was used for doubling frequency of the quasi-CW broad fiber laser. The spectra of second harmonic at different temperature are achieved and discussed in detail.