Design of All-Optical Modulation Format Converter From One 8PSK to Two QPSK Signals Based on Phase Sensitive Amplification in Elastic Optical Network

Flexible conversion between modulation formats enables intelligent grooming techniques for an elastic optical network (EON) aimed at dynamical spectral efficiency allocation in optical fiber transmission. In this paper, we propose and demonstrate an all-optical modulation format conversion scheme between an 8-ary phase shift keying (8PSK) signal and two quadrature phase shift keying (QPSK) signals based on phase-sensitive amplification in highly nonlinear fiber. Benefiting from two simultaneous but different phase-squeezing processes, the two QPSK signals can be obtained simultaneously to avoid the loss of original information. The system transfer functions show the feasibility of the proposed scheme, and the system performance is evaluated by input-output constellations, calculated error vector magnitude (EVM), and bit error rate (BER) in numerical simulation. At BER of 3.8 × 10
^-3
, about 5-dB optical signal-to-noise-ratio (OSNR) improvement between the input 8PSK signal and output QPSK signals can be observed. Furthermore, several potential applications in optical fiber transmission can also be found based on the converter.