An Approach for Increasing User Capacity of OCDMA System Based on Vernier Effect

Abstract

A structure of serially coupled dumbbell microring resonator (SCDMRR) is proposed based on vernier effects to obtain wider free spectral range (FSR), and a new kind of two-dimensional optical en/decoder is designed taking advantage of the SCDMRR. Numerical simulations are done to analyze reflection spectrum of the SCDMRR and test performance of the proposed en/decoder according to the coupled mode theory. In addition, the coupling coefficients of both ring-bus and ring-ring are optimized to suppress the spurious mode. Furthermore, a comparison is performed between the en/decoder based on SCDMRRs and the en/decoder using ordinarily coupled identical three-order-ring resonators (OCITRR). The results show that the FSR is 13nm for SCDMRR with the ring radius of 40um-30um-40um, which is about four to five times larger than that of OCITRR. Such FSR will contain more column numbers of parallel-coupled MRR and the code cardinality generated by the proposed device is 3.43E17. For the SCDMRR-based en/decoder, the peak to wing ratio (P/W) of auto-correlation signal and peak power ratio (P/C) between the auto-/cross-correlations are 6.39 and 8.71, which have risen by approximately 33% and 8% against that of en/decoder based on OCITRR, respectively.