Multi-Carrier Coherent Receiver Based on a Shared Optical Hybrid and a Cyclic AWG Array for Terabit/s Optical Transmission

: We describe a multi-carrier coherent receiver scheme where the coherent beating between an ultra-high-speed multi-carrier signal and multiple optical local oscillators (OLOs) is conducted in a single optical hybrid, followed by carrier separation through an arrayed waveguide grating (AWG) array. Sharing the optical hybrid for multiple OLOs simplifies the coherent receiver complexity and easies timing alignment among multiple modulated carriers. Based on this scheme, a compact coherent receiver front-end consisting of an integrated 4x40 AWG array following a polarization-diversity optical hybrid is demonstrated, and used for complete demodulation of a 1.12-Tb/s multi-carrier-signal having ten 112-Gb/s PDMQPSK carriers spaced at 50 GHz. The required optical signal-to-noise ratio for the 1.12-Tb/s signal is 27 dB at 10-3 bit error ratio. The cyclic feature of the AWG array allows the receiver to receive modulated carriers that are not adjacently spaced. We also extend this receiver scheme for multi-carrier signals whose carriers are close spaced, e.g., under the orthogonal frequency-division multiplexing (OFDM) condition, for high spectralefficiency Tb/s transmission applications. 2009 Optical Society of America OCIS codes: (060.1660) Coherent communications; (060.5060) Phase modulation; (060.2330) Fiber optics communication.