High performance integrated coherent transceivers for optical access networks

Coherent communication system has well-known advantages of high receiver sensitivity, high channel packing density, and flexibility in channel selection. Implementation of coherent detection in optical subscriber network for TV distribution and broad-band ISDN services have been demonstrated. Monolithically integrated coherent receivers is attractive for such applications, due to the dramatic cost reduction by eliminating packaging of hybrid components. However, the device structure as well as fabrication process of integrated receivers are usually quite complex and the yield is considerably low. We proposed and demonstrated an integrated device with simple structure can perform both transmitting and receiving functions with very high receiver sensitivity. The device structure and possible configurations as customer transceiver in coherent multi-carrier (CMC) distribution system is shown. The device is composed of a tunable DBR laser as a local oscillator (LO) and an integrated detector. This allows one to fully utilize the wavelength tuning range to achieve highly dense spaced WDM coherent systems.