Calculation of Bit Error Rates in Optical Systems With Silicon Photonic Wires

A theoretical approach to calculate the bit error rate (BER) in optical systems containing silicon photonic wires (Si-PhWs) is presented. Specifically, the optical link consists of a single-mode silicon-on-insulator strip waveguide followed by a direct-detection optical receiver containing an optical filter, an ideal square-law photodetector, and an electrical filter. We assume that the optical input consists of a superposition of a nonreturn-to-zero ON-OFF keying modulated optical signal and an additive white Gaussian noise, the BER of the transmitted optical signal being calculated using the time domain Karhunen-Loève expansion method. The propagation of the optical signal in the Si-PhW is described by employing both a rigorous theoretical model that incorporates all relevant linear and nonlinear optical effects and the mutual interaction between the free carriers and the optical field, as well as a linearized model valid in the low-noise power regime. These analytical and computational tools are then used to comprehensively investigate the influence of the parameters characterizing the waveguide and optical signal on the transmission BER.