All-optical wavelength conversion using SOA at nearly symmetric position in a fiber-based sagnac interferometric loop

We report an experimental analysis of the wavelength conversion operation of a fiber-based Sagnac interferometric loop with a semiconductor optical amplifier (SOA) at nearly symmetric position. Improved extinction ratio is obtained due to the complementary operation of cross-polarization modulation and cross-gain modulation effects. Power penalty of 2.4 dB was obtained when the SOA offset is 17% of the bit period, which enables the use of the Sagnac interferometer with asymmetrically placed SOA-the terahertz optical asymmetric demultiplexer (TOAD)-as a multiple-functionality all-optical signal processing network element.