用超模理论分析光栅耦合器型滤波器的特性

Analysis of the Grating-in-Coupler Filters by Using Supermode Theory

从实际测量的耦合器的形状出发,运用耦合的超模理论分析了在普通2×2光纤耦合器的熔锥区写入光栅制作滤波器的特性,并对不同类型的耦合器进行了比较。研究表明,即使在普通的耦合器上写入布拉格光栅,同样可以获得波长选择滤波器,并且存在最佳光栅位置和光栅长度。同时提出了获得窄线宽、边带抑制的滤波器的新方法,即在熔锥区写入非线性啁啾光栅。

Taking into account the shape of the coupler, characteristics of conventional 2×2 fused coupler incorporated with Bragg grating is numerically investigated and analyzed by using supermode theory. Comparison between different types of couplers is carried out. Simulation results show that wavelength-selective-filter based on conventional fused coupler can be realized by imprinting the grating with appropriate length in an optimized position. Moreover, a new method is proposed to obtain narrow bandwidth and side-lobe suppressed spectrum of this component, namely, writing a nonlinear chirped grating instead of the uniform one into the coupler.