Optimization and simulation of micrometre-scale ring resonator modulators based on p-i-n diodes using firefly algorithm

Field analysis of ring resonator modulators based on p-i-n diodes has been dissected in this paper. This analysis is performed in time and frequency domains. The conformal transformation method has been used for solving 3-D wave equation. Coupling coefficient between the ring and straight waveguides are obtained by developing the coupled-mode assumption. In the resonant wavelength of 1573.91 nm, a drop of more than 15 dB in frequency spectrum of the device has been observed. Time domain simulation shows that this modulator could support up to 0.4 Gb/s and up to 1.5 Gb/s for NRZ and RZ signals, respectively. Obtained simulation results in both domains have been properly complied with experimental results. Main goal of this paper is to present an optimized model from aforementioned modulator. It will be shown that frequency response could be more optimum than original device by optimizing structure parameters. In order to obtain practical values, Firefly Algorithm (FA) is used because it finds optimum points locally. In optimized modulator, extinction ratio (ER) could be increased up to 32 dB which is double than original modulator.