准相位匹配级联二阶非线性全光波长转换研究

Study of Quasi-Phase-Matched Cascaded χ^(2) All-Optical Wavelength Conversion

对基于级联和频差频非线性效应铌酸锂光波导新型全光波长转换器进行了理论研究。这种新型波长变换器需要两束抽运光源,它将输入的抽运光波长置于信号光波段窗口的两边,抽运光波长与信号光波长相近容易实现最佳耦合又不会占用信号波段,而且具有偏振不敏感的优点。从建立级联和频差频铌酸锂光波导全光波长转换器的理论模型出发,给出了波导中光相互作用的耦合模方程;利用逐步法详细推导了耦合模方程的解,得出了物理意义清晰的转换光功率表达式,分析了非线性晶体相互作用长度、抽运光功率对转换效率的影响,为级联和频差频铌酸锂光波导全光波长转换器优化设计提供了理论依据。

A novel all-optical wavelength conversion (AOWC) based on the cascaded sum frequency generation (SFG) and difference frequency generation (DFG) in LiNbO3 waveguides have been theoretically studied. This novel wavelength convertor employing two pump sources places the two input pump wavelengths outside the optical communication band. It is easily realize optimum coupling between punp wavelengths and signal wavelength since their wavelengths are relatively close to each other and the pump wavelenths do not occupy the communication band and the convertor has a characteristic of polarization-insensitive. The theoretical model of the AOWC is established and the coupled-mode equations of optical interaction in waveguide are given out. Then the solutions of coupled-mode equations are in detail deduced step by step and an electric field expression of clear physical insight is obtained. The effects of the device length and the pump powers on the conversion efficiency are analyzed, and it offers theoretical foundation for the optimum frabrication parameters for stable and highly efficient AOWC.