Bidirectional transmission with a single fiber using FWM for WDM-PON

This paper investigates bidirectional transmission using four wave mixing (FWM) for wavelength division multiplex passive optical network (WDM-PON) applications. A semiconductor optical amplifier (SOA) is considered to generate FWM. A use of FWM makes it possible to convert a downstream data wavelength to a different wavelength, which is used for upstream transmission. The wavelength generated by FWM can realize bidirectional transmission with a single fiber. We assume intensity modulation (IM) for both up- and down-transmission. Both an injection locked Fabry-Perot laser diode (FP-LD) transmitter and a transmitter with an external modulator are considered for upstream transmission. In both cases, an extinction ratio (Ex) of downstream signal light is very important for both sending and receiving properties and the Ex influences the bit error rate (BER) property. This paper clarifies the relationship between the Ex of FWM and the power penalty AP. This paper also clarify the Ex value of FWM as a function of input signal Ex using a model SOA theoretically. Fundamental transmission experiments, 10 Gbit/s downstream and 2.5 Gbit/s upstream, using both types of transmitters confirmed the possibilities of the bidirectional transmission using FWM.