Double S-bend structure for a compact two mode interference coupler

摘要

A double S-bend structure has been proposed for the reduction of coupling length of the 2 X 2 two mode interference (TMI) coupler. The coupling characteristics of the proposed structure are compared with those of conventional TMI structures using a simple mathematical model based on sinusoidal modes. The longitudinal beat length for the proposed TMI coupler is reduced by 15percent of the beat length of a conventional TMI coupler. The effect of power imbalance on fabrication tolerance of the proposed TMI coupler is also studied and compared with other TMI couplers.