Modulated Raman Pump for Integrated VCSEL-based Reach Enhancement and Clock Tone Dissemination in Optical Communication

The fast growth of data traffic in access networks calls for high speed and low-cost optical links. To extend reach for users in metro areas requires optical amplification of the signal carrying data. In this paper we experimentally demonstrate a cost effective technique of extending reach by exploiting Raman pump to both amplify data signal and transmit clock signals. A 1550 nm VCSEL is modulated with a 10 Gbps data and coupled into a 50.7 km fibre to co-propagate with a 4 GHz modulated Raman pump. Error free and enhanced data transmission was achieved with minimum receiver sensitivity of -14.8 dBm and distributed stable clock signal over 50.7 km SMF-Reach. A maximum phase noise of -100.6 dBc/Hz at 10 kHz offset frequency is experimentally measured for 50.7 km fibre transmission with backward Raman amplification. This work presents a real-time technique of transmitting accurate data and stable clock signal for long-reach optical networks.