Polarization diversity DPSK demodulator on the silicon-on-insulator platform with simple fabrication

Yunhong Ding,Haiyan Ou,Bo Huang,Christophe Peucheret,Francesco Da Ros

doi:10.1364/oe.21.007828

Abstract

We demonstrate a novel polarization diversity differential phase-shift keying (DPSK) demodulator on the SOI platform, which is fabricated in a single lithography and etching step. The polarization diversity DPSK demodulator is based on a novel polarization splitter and rotator, which consists of a tapered waveguide followed by a 2 × 2 multimode interferometer. A lowest insertion loss of 0.5 dB with low polarization dependent loss of 1.6 dB and low polarization dependent extinction ratio smaller than 3 dB are measured for the polarization diversity circuit. Clear eye-diagrams and a finite power penalty of only 3 dB when the input state of polarization is scrambled are obtained for 40 Gbit/s non return-to-zero DPSK (NRZ-DPSK) demodulation.

Highlights

The differential phase-shift keying (DPSK) format is widely used in optical communication networks due to its better fiber nonlinearity tolerance [1]
We demonstrate a novel polarization diversity differential phaseshift keying (DPSK) demodulator on the SOI platform, which is fabricated in a single lithography and etching step
The polarization diversity DPSK demodulator is based on a novel polarization splitter and rotator, which consists of a tapered waveguide followed by a 2 × 2 multimode interferometer

Summary

Introduction

The differential phase-shift keying (DPSK) format is widely used in optical communication networks due to its better fiber nonlinearity tolerance [1]. The use of silicon microring resonators (MRRs) has been proposed and demonstrated for ultra-compact DPSK demodulation [6, 7]. One is based on two-dimensional grating couplers, which work on a particular polarization and play the role of a polarization splitter [9,10,11,12] This scheme is limited by the insertion loss and bandwidth of the grating coupler. Another method is based on polarization splitter and rotator (PSR) technology [13,14,15,16,17,18]. A Pol-D circuit for NRZ-DPSK demodulation relying on an asymmetrical coupler-based PSR has been demonstrated [19]. Compared to a standard MRR demodulator without polarization diversity, the use of the proposed Pol-D structure results in a clear eye-diagram and finite power penalty of only 3 dB when the input state of polarization is scrambled

Polarization splitter and rotator

Polarization diversity NRZ-DPSK demodulator

Fabricated device

NRZ-DPSK demodulation with reduced polarization sensitivity

Findings

Conclusion