Fiber-optic parametric amplifier-based all-optical format conversion enabling optical networks interconnection with different modulation formats

Abstract

A fiber-optic parametric amplifier (FOPA)-based all-optical format conversion (AOFC) scheme is proposed and numerically simulated to achieve optical networks interconnection with different modulation formats. In this scheme, the power transfer function (PTF) and the relative phase shift (RPS) functions between the input and output optical signals for the single-pump FOPA are derived and numerically analyzed. For the input 20 Gbps bipolar 4-ary pulse amplitude modulation (PAM4) signal, it can be converted into a BPSK signal (BPSK1) based on the power saturation characteristic of the PTF. By adjusting the input power of the input PAM4 signal, it can also be converted into a level-swapping PAM4 signal based on the single-pump FOPA. When the level-swapping PAM4 signal is sent into the single-pump FOPA with suitable power again, another BPSK signal (BPSK2) could also be generated. When the PAM4-to-BPSK format converter based on the single-pump FOPA is combined with the dual-pump FOPA (namely phase-sensitive amplifier, PSA), the 16-ary quadrature amplitude modulation (16QAM) signal can also be de-aggregated into four BPSK signals or two quadrature phase shift keying (QPSK) signals. The constellation diagrams, the power waveforms, the error vector magnitude (EVM) and the bit error rate (BER) of the relevant optical signals are measured to evaluate the scheme performance. The scheme can be deployed at the optical gateway to realize optical networks interconnection using different modulation formats.