Generation of 60 GHz Dual-Mode Optical BPSK Signal Pair for Crosstalk-Free QPSK Photodetection by Optical Modulation Scheme with Double RF Inputs and Suppressed Carrier Feature

摘要

A novel optical modulation scheme is proposed for synthesizing a pair of dual-mode optical BPSK signals with an orthogonal phase relationship via a LiNbO_3 Mach-Zehnder modulator (MZM) with dual RF signal inputs and a carrier suppression feature, which enables the generation of a crosstalk-free QPSK signal at the photodetection stage. With this method, one can compensate the drawback, that is bandwidth broadening, in our previously proposed method where a dual-mode optical QPSK signal is generated on the basis of narrow-angle modulated QPSK signal injection into a double-sideband suppressed carrier MZM device. We have carried out experiments for 60 GHz performance demonstration of this QPSK signal generation mechanism, and the results indicate the effectiveness of the present scheme.