Phase-sensitive Amplification in Semiconductor Optical Amplifiers using Four Wave Mixing

Abstract

Optical communication is realized by encoding digital information in an optical carrier and propagation through optical fibers. These carriers, however, undergo attenuation as they propagate and have to be amplified periodically to mitigate the losses. The commonly used in-line amplifiers are phase insensitive, and also add noise during amplification. Phase sensitive amplification is a technique which selectively amplifies one field quadrature and attenuates the other, which helps to achieve low noise amplification of optically transmitted data. It has been widely studied for implementation in optical communication, squeezed state generation, gravitational wave detection, among other applications. In this project, this technique has been studied using the nonlinear phenomenon of four wave mixing in a semiconductor optical amplifier medium. We first explore the theory of four wave mixing in the semiconductor amplifier medium and the conditions influencing the process. Next, four wave mixing in different configurations of input optical fields are analysed and compared. All the studies have been done by performing numerical simulations in MATLAB software. The theory of four wave mixing developed is further used to study the different schemes of phase sensitive amplification. This has been done for two phase modulated data formats. The four wave mixing configurations necessary to achieve phase squeezing for the data formats have been examined.