Rayleigh Backscattering Rejection in Single-Laser Homodyne Transceiver for UD-WDM Using λ-Shifting

Abstract

With the aim of using a single laser in single fiber splitter-based Passive Optical Networks (PON) with coherent homodyne transceivers, we apply wavelength shifting in an ultradense Wavelength Division Multiplexing (ud-WDM) scheme. The studied architecture is based on IQ modulator operating in Carrier-Suppressed Single-Sideband (CS-SSB). In this configuration, a single laser feeds both the coherent homodyne receiver, and the transmitter, simplifying the wavelength management in the PON. The modulator carries out both data modulation and wavelength shifting. In this study, a bit rate of 4 Gbit/s in QPSK is used to test several roll-off factors and channel spacing configurations. The results sh ow that power budget gains of 18 dB are achievable with a channel spacing equal to only the symbol rate.

Coherent UD-WDM RoF Fronthaul Network With D-EML Transmitter and Phase-Noise Robust Receiver

“…They are optically separated 2.5 GHz. The modulation of ch.1 has been obtained for mIM = 0.4 and mFM = 0.1, again in the maximum linearity region of the EAM, and the modulation of ch.2 has been generated by operating the IQ modulator in OSSB configuration [12,13], with modulation biases shifted from the null point so a residual carrier is left, obtaining a carrier-tosignal ratio of about 5 dB to approximate the modulation of the D-EML. The signals of ch.1 and ch.2 were uncorrelated in time by different physical path differences.…”