Colorless WDM-PON Optical Network Unit (ONU) Based on Integrated Nonreciprocal Optical Phase Modulator and Optical Loop Mirror

To reduce the complexity and costs of optical network unit (ONU) transceiver, we propose a scheme based on a nonreciprocal optical phase modulator and a linear optical loop mirror for sending upstream data in a wavelength-division-multiplexing passive optical network. We show that the nonreciprocity of traveling-wave electrodes can selectively impress phase modulation onto the reflected upstream signals only. Monolithic integrated transceivers may thus remodulate downstream signals for upstream data transmission without needing integrated optical circulators. The proposed ONU is thus compatible with monolithic integration.