Bidirectional 50 Gb/s/λ WDM-PON based on optical intensity modulation and direct detection

We experimentally demonstrate an optical intensity modulation transmitter with a half-cycle 32 QAM Nyquist subcarrier modulation and direct detection receiver-based channel-reuse wavelength-division-multiplexing passive optical network. Chromatic dispersion-induced power fading in the direct detection system is avoided with fiber Bragg grating filter-based vestigial-sideband filtering. The inter-symbol interference is mitigated with a digital signal processing-based overlap frequency-domain equalizer and iterative distortion-cancellation technique. A frequency division multiplexing-based wavelength management method is employed for the tunable laser used in a colorless optical network unit to achieve a bidirectional 50 Gb/s/λ transmission over a 40 km-long standard single-mode-fiber on a 100 GHz WDM grid. The transmission performance is also measured with different central wavelength shifts between upstream and downstream in the channel-reuse system.