Ultrafast All-Optical Signal Processing Based on Single Semiconductor Optical Amplifier and Optical Filtering

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> We propose and demonstrate several all-optical signal-processing technologies, including wavelength conversion (WC), leading/trailing edge detection, and logic gates based on a semiconductor optical amplifier (SOA) and a detuning optical bandpass filter (OBF). The system is based on pump-probe scheme. When the pump signal is return-to-zero (RZ) format, both inverted WC and noninverted WC at 40 Gb/s are obtained, and the polarity variation is highly dependent on the OBF detuning. When the pump signal is nonreturn-to-zero (NRZ) format, both the inverted WC and leading/trailing edge detection are obtained. In the inverted WC, the OBF detuning is small, and it helps to accelerate the amplitude recovery. However, in the noninverted WC and pulse edge detection, the OBF detuning is relatively large, and it acts as frequency–amplitude conversion. Finally, we present all-optical reconfigurable logic gates based on various nonlinearities in an SOA. The logic gates including <emphasis emphasistype="smcaps">and</emphasis>, <emphasis emphasistype="smcaps">nor</emphasis>/<emphasis emphasistype="smcaps">not</emphasis>, and <emphasis emphasistype="smcaps">or</emphasis> are obtained by four-wave mixing, cross-gain modulation, and transient cross-phase modulation in the SOA, respectively. The <emphasis emphasistype="smcaps">nor</emphasis> and <emphasis emphasistype="smcaps">or</emphasis> gates are capable of operating at 40 Gb/s with the help of the OBF detuning. The <emphasis emphasistype="smcaps">xnor</emphasis> gate is implemented by combining the <emphasis emphasistype="smcaps">and</emphasis> output and <emphasis emphasistype="smcaps">nor</emphasis> output. </para>