Polarization-Independent All-Optical Regenerator for DPSK Data

Valeria Vercesi,Claudio Porzi,Antonella Bogoni,Giampiero Contestabile

doi:10.3390/photonics1020154

Abstract

We demonstrate polarization-independent simultaneous all-optical phase-preserving amplitude regeneration and wavelength conversion of NRZ differential phase shift keying (DPSK) data by four-wave mixing (FWM) in a semiconductor optical amplifier (SOA). The dependence upon polarization state of the signals is eliminated by using a co-polarized dual-pump architecture. Investigation on the regenerative capability vs. pumps detuning shows significant BER threshold margin improvement over 6 nm conversion range.

Highlights

Optical networks continue to evolve in response to ever-increasing levels of traffic, with a growing emphasis on network flexibility
Among phase-preserving schemes, those based on semiconductor optical amplifier (SOA) offer the additional benefits of compactness, low-operating power levels and wide operating bandwidth, and we recently demonstrated strong regeneration of NRZ-differential phase shift keying (DPSK) signals over a broad conversion range of about 50 nm [9]
The power level of the output Four-wave mixing (FWM) terms depends on the pumps detuning ∆λP = |λP1 − λP2|, and it is insensitive to input signal polarization and wavelength, as long as the SOA PDG is negligible and the beating due to the two pumps is stronger than the beatings due to signal and pumps

Summary

Introduction

Optical networks continue to evolve in response to ever-increasing levels of traffic, with a growing emphasis on network flexibility. Four-wave mixing (FWM) effect in both fibers [6] and semiconductor optical amplifiers (SOAs) [7,8] has been proposed to perform phase-modulated signals amplitude regeneration without altering their phase information by introducing excess phase noise. The advantage of this phase-preserving amplitude regeneration approach for phase-modulated data relies in a simpler implementation in respect to coherent architectures and in interferometer-based schemes. The efficient amplitude regenerative characteristic of FWM-based wavelength conversion with limited excess phase noise in SOAs, is preserved in presence of the two co-polarized pumps scheme, enabling polarization-independent regenerative wavelength conversion. The regenerative capability and the robustness of the system against conversion range are investigated, demonstrating Q-factor enhancement and corresponding BER threshold margin improvement with fair values of optical signal-to-noise ratio (OSNR) and FWM conversion efficiency within a range of 6 nm for an NRZ-DPSK 10 Gb/s data signal

Set-Up and Principle

Experimental Results

Conclusions