根据耦合模理论,推导出可调谐光波导谐振环的光强和相位传递函数的表达式,并分析了可调谐谐振环的传输特性。结果表明,谐振环中集成的马赫曾德尔耦合器的参量设定和调谐方式直接影响谐振环的谐振频率移动范围和调制功率。通过改变耦合器参量对谐振环进行优化设计,在中心波长为1550 nm附近,谐振环半径2 cm,传输损耗0.08 dB/cm的情况下,实现了清晰度和最佳谐振深度的调谐,谐振频率的移动范围低于0.027 GHz,降低了谐振环对频率调制器的调频要求,同时降低了耦合器的调制功率。

The transmission characteristics of optical waveguide ring resonator with tunable Mach-Zehnder interferometer (MZI) are analyzed. The formulas of the intensity and phase transfer functions are deduced according to the coupled-mode theory. It shows that the resonant frequencies shift range and the modulation power of Mach-Zehnder interferometer are heavily dependent on the parameters of Mach-Zehnder interferometer. An optimized design for ring resonator is demonstrated, the numerical ring modeling with the radius of 2 cm and the propagation loss of 0.08 dB/cm is performed around the central wavelength of 1550 nm, the resonant frequencies shift range is lower than 0.027 GHz, and the maximum notch depth is obtained, it means that the frequency modulator with small bandwidth can be used for the ring resonator and the finesse can be tuned with lower power.