Four-input NOR gate using cross gain modulation in a single Semiconductor Optical Amplifier

We demonstrate all-optical NOR logic operation of four data signals in one SOA. Exploiting XGM, wavelength multiplexing and optical filtering for signal discrimination, we purpose an implementation in which an all-one optical probe signal is modulated by the optical sum of four different data signals at 10 Gbps each. Data signals act as pump and reduce the gain of the SOA producing on-off keying of the probe and, hence, the NOR behavior. We derive the feasibility of a multiple-bit NOR from a simple XGM setup working at a wide range of pump power by means of a characterization with all-one RZ streams. High-resolution measures of the signals are presented to illustrate nonlinear effects and wavelength management. Signals traces are showed to prove logic functioning and 4-bit gate quality is reported by means of eye diagrams of the output signal for different input powers.