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.