Photonic integrated circuit (PIC) transceivers for an optical line terminal (OLT) and an optical network unit (ONU) in passive optical networks (PONs)

摘要

A photonic integrated circuit (PIC) for a PON transceiver comprises a single monolithic chip having a modulated transmitter laser diode of a first wavelength, lambda₁, for generating a first communication signal outgoing from the chip via an input/output port and a receiving photodetector for receiving a second communication signal of a second wavelength, lambda₂, onto chip incoming from the input/output port and a monitoring photodetector for receiving a portion of the first communication signal to monitor the laser diode output power. In one embodiment, the chip is provided with multimode (MM) coupler set to direct a substantial portion of the incoming communication signal to the receiving photodetector and to direct a substantial portion of the outgoing communication signal to the input/output port. A filter may be inserted before the receiving photodetector and/or the laser diode to extract any remaining and undesired signal to either such electro-optic elements. In another embodiment, the laser diode, power monitoring photodetector and the receiving photodetector are collinear in the same chip having a common waveguide where the power monitoring photodetector is capable of both monitoring power and insuring no backward reflecting light of the laser diode reaches the receiving photodiode through it absorption of such light. The active region of the power monitoring photodetector can be set to be absorptive of incoming of backward reflected polarized light of both the TE and TM polarization modes respectively from the chip input or the on-chip laser diode.