Wavelength Reuse in a UWB Over WDM-PON Based on Injection Locking of a Fabry–Pérot Laser Diode and Polarization Multiplexing

Wavelength reuse in a symmetric ultra-wideband (UWB) over wavelength-division-multiplexing passive optical network based on injection locking of a Fabry-Pérot laser diode (FP-LD) and polarization multiplexing is proposed and experimentally demonstrated. In the proposed scheme, the downstream UWB signal and baseband signal are generated and polarization multiplexed in the central station and sent to a base station (BS) over an optical fiber. At the BS, one of the downstream signals is selected to injection lock the FP-LD. It is demonstrated theoretically and experimentally that the upstream service performance is less sensitive to the modulation depth of the downstream UWB signal than the baseband signal, and the use of the downstream UWB signal as the injection signal would contribute to a better transmission performance for both the downstream and upstream services. Thus, the downstream UWB signal is selected as the injection signal. An experiment is performed. When the FP-LD is injection locked by a downstream UWB signal, a clear optical carrier is generated which is reused for upstream UWB and baseband transmission. A bidirectional point-to-point transmission of 1.25 Gb/s UWB signal and 10 Gb/s baseband signal over 25-km single-mode fiber using a single wavelength is demonstrated. The bit error rate performances and the eye diagrams for both downstream and upstream transmissions are measured.