Wang Yujia, Grieco Andrew, Nguyen Truong
Opt Express. 2013 Dec 30;21(26):32040-52. doi: 10.1364/OE.21.032040.
A major artifact of realistic photonic filters is the waveguide power loss. Its detrimental effect on the allpass structure is particularly alarming because the phase response is highly sensitive to perturbations. While the loss can be simply captured into a variation on the unit delay in signal processing analysis, its non-linearity makes it mathematically difficult to address. We present an allpass filter design algorithm that is able to provide filter coefficients that compensate for the waveguide power loss. By absorbing the loss parameter into the design cost function, the optimization problem becomes non-convex and NP hard. Our approach solves this problem by utilizing an iterative algorithm in conjunction with the branch and bound global optimization technique. The proposed algorithm is expected to improve the performance and increase the utilization of allpass filters for optical signal phase based applications such as distortion compensation and group delay equalization.
实际光子滤波器的一个主要伪像是波导功率损耗。它对全通结构的有害影响尤其令人担忧，因为相位响应对扰动高度敏感。虽然在信号处理分析中，损耗可以简单地归结为单位延迟的变化，但其非线性使得在数学上难以处理。我们提出了一种全通滤波器设计算法，该算法能够提供补偿波导功率损耗的滤波器系数。通过将损耗参数纳入设计成本函数，优化问题变得非凸且为NP难问题。我们的方法通过结合迭代算法和分支定界全局优化技术来解决这个问题。预计所提出的算法将提高性能，并增加全通滤波器在基于光信号相位的应用中的利用率，如失真补偿和群延迟均衡。
