Differential Monitoring of AWG-Filtered Reflection Signal for Accurate Transmitter Power Control of Injection-Locked WDM PON Systems

We propose a simple and robust, automatic power control architecture for the injection-locked, wavelength-division-multiplexed passive optical network system. Monitoring the differential of reflected signal power from the mid-stage fiber mirror placed after the arrayed waveguide grating in the central office, the problem of transmitted signal power fluctuation experienced in conventional, back-facet photodiode monitoring schemes is eliminated. Results show the excellent control of the transmitted power within a peak-to-peak fluctuation of 0.1 dB over a wide operating range of temperature and injection power level.