Comprehensive analysis of two cascaded semiconductor optical amplifiers for all-optical switching operation

This paper presents numerical calculations and experimental results for two cascaded semiconductor optical amplifiers (SOAs) in a counterpropagating configuration for an all-optical switching operation. A detailed theoretical analysis with regard to the gain evolution and the extinction ratio (ER) through the SOAs´ cavities show that the two cascaded SOAs have improved performance over the single SOA configuration. A measured ER up to 20 dB is obtained for close contra-directional signal wavelengths and for a wide range of optical input powers. An all-optical switching operation is realized for 2.5-GHz data pulses, and its feasibility is demonstrated with an ER higher than 12 dB over a wide range of wavelength.