Polarization-multiplexed, 10Gsymbol/s, 64QAM coherent transmission over 150km with OPLL-based homodyne detection employing narrow linewidth LDs

Abstract

Abstract:We report a polarization-multiplexed 10 Gsymbol/s, 64 QAM (120 Gbit/s) coherent transmission over 150 km by using an optical phase-locked loop (OPLL) circuit employing narrow linewidth LDs. The OPLL realized low phase noise demodulation of 64 QAM signal. As a result, 120 Gbit/s data signal were transmitted with a bit error rate (BER) performance below a forward error correction (FEC) threshold of 2 × 10 −3 .

60 Gbit/s, 64 QAM LD-based injection-locked coherent heterodyne transmission over 160 km with a spectral efficiency of 9 bit/s/Hz

“…In coherent transmission, phase synchronization between transmitted data and a local oscillator (LO) is indispensable especially for high multiplicity modulation in quadrature amplitude modulation (QAM) transmission. For data, some phase synchronization schemes have already been developed with software [2,3] or hardware circuits [4,5]. Among them, an injectionlocking scheme is a very interesting way to realize low phase noise carrier synchronization with a simple receiver configuration [6].…”