Robust modeling of SOI-based optical phase modulator using free carrier dispersion effect

This paper reports the effect and optimization of design parameters of a silicon-on-insulator (SOI) optical waveguide phase modulator using Taguchi method. The modulator employing the p-i-n diode structure will be working based on free carrier dispersion effect at 1.55 mu m optical telecommunication wavelength. The optimization is focus to minimize the tradeoff between refractive index change and absorption loss in the device's performance. Four design parameters were explored, namely applied voltage, doping concentration, doping position and waveguide rib area. In addition, four noise factors were also included to achieve robustness of the proposed device design which is the annealing temperatures for both the p-doped and n-doped wells as well as the phosphorous and boron implant energy for both the p-doped and n-doped wells. The level of importance of the design parameters on the refractive index change and absorption loss were determined using Analysis of Variance (ANOVA). The optimum process parameter combination was obtained using the analysis of Signal-to-Noise (S/N) ratio. It was discovered that the applied voltage is the most dominant factor in determining the response of the modulator. The results show that the refractive index change and absorption loss upon Taguchi optimization is 0.00155 and 19.9dB/cm respectively.