Design of an all-optical NOT XOR gate based on cross-polarization modulation in a semiconductor optical amplifier

Abstract

In this work, we have discussed the physical phenomena involved in the manifestation of the cross-polarization modulation (XPolM) effect in a semiconductor optical amplifier (SOA), namely the eigenaxes modification, the structural birefringence perturbation and the polarization gain dispersion. We demonstrate that the XPolM effect can rotate the polarization-state of a CW beam by 73.5° when the power of a control beam changes from 0 to 300 μW. The control and CW beams are introduced into the amplifier with a linear polarization near to the unperturbed amplifier TM axis where the waveguide eigenaxes modification presented the strongest participation in the XPolM effect in the used SOA. Finally, we experimentally show Boolean NOT XOR operation with input logic signals modulated with a 2.5 Gb/s NRZ code with a pseudo-random data sequence of 2 23−1 length. The NOT XOR gate utilizes a single SOA as non-linear element and it needs neither an inversion stage nor an additional synchronized clock.