Open AccessCompensation of SOA-induced nonlinear phase distortions by optical phase conjugation
Author(s) -
Aneesh Sobhanan,
Mark Pelusi,
Takashi Inoue,
Deepa Venkitesh,
Shu Namiki
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.416955
Subject(s) - optical amplifier , optics , wavelength division multiplexing , amplifier , quadrature amplitude modulation , distortion (music) , signal (programming language) , physics , compensation (psychology) , optical power , cross phase modulation , phase distortion , transmission (telecommunications) , phase (matter) , phase modulation , phase noise , telecommunications , optoelectronics , computer science , channel (broadcasting) , bit error rate , wavelength , psychology , laser , cmos , quantum mechanics , psychoanalysis , programming language
To answer the question: "Is optical phase conjugation (OPC) capable of compensating nonlinear distortions caused by not only Kerr effect of optical fibre, but also the carrier dynamics of semiconductor optical amplifiers (SOAs)?", we investigate the effectiveness of OPC-based nonlinear compensation for SOAs amplifying a few-channel WDM signal modulated with m-QAM. We use a pair of SOAs with an OPC stage sandwiched between the two so that the combination works as a low-distortion amplifier. Symbol-period longer than the gain recovery time is chosen in our experiments to avoid bit-pattern effects introduced by the SOA. We amplify a 12Gbaud, 16QAM modulated three-channel WDM signal with this technique in the back-to-back configuration which remarkably outperforms a single SOA in the nonlinear regime of operation with an average Q 2 improvement better than 4 dB for an output power of 4 dBm. We further demonstrate the practical advantage of the low distortion higher output power capability of the SOA shown in the back-to-back result by carrying out a transmission of the amplified signal through a 160-km fibre, where relatively high launch power is desirable. We also study the case of 64QAM signals and show that approximately a 3 dB Q 2 factor improvement can be obtained over single SOA, while without nonlinear phase distortion compensation, the demodulation is nearly impracticable.