Penalty-Free Semiconductor Optical Amplifier Wavelength Conversion of 32-GBd 4-QAM Optical Carriers

The wavelength conversion of 4-ary quadrature amplitude modulation (4-QAM) optical carriers is achieved for small input powers (<; -15 dBm) and symbol rates of 32 GBd using a highly nonlinear semiconductor optical amplifier (SOA). The degenerated four-wave mixing (FWM) phenomena was used in order to avoid secondary FWM products and gain saturation. With optimized input powers and wavelengths to achieve maximum FWM efficiency, error-free operation was achieved with negligible penalties employing conventional digital signal processing (DSP) algorithms for signal recovering, demodulation, and analysis.