复合型变耦合系数定向耦合器开关特性的研究

研究了高斯—常数—高斯平滑连接的复合型变耦合系数定向耦合器的开关特性曲线。研究了耦合器各分段长度对开关曲线的影响。数值模拟发现，耦合器各组成部分的参量对耦合器开关曲线尾部的振荡及开关功率的大小均有影响，且呈现出一定的规律性。高斯型波导部分的相对长度以及直波导部分所占份额共同决定了耦合器开关曲线尾部的振荡大小，且开关曲线的振荡与耦合函数的傅里叶变换的振荡密切相关。

Analysis of the Switching Characteristics of Complex Varying Coupling Coefficient Nonlinear Directional Coupler

The characteristics of the switching curves of Gaussian-Constant-Gaussian varying coupling coefficient nonlinear directional coupler (GCG NLDC) are analyzed in detail. The influences of the parameters of the coupler's subsections on the switching curves are studied. It is found by numerical simulation that the existence of sidelobes of the switching curves and the value of the switching powers are related to the parameters of all the subsections. The magnitude of sidelobes of the switching curves is decided by the relative length of bent coupler L/b and the quotient of conventional NLDC, the sidelobes of the switching curves have close relations with the oscillation of the Fourier transforms of the coupling functions.