Design of a silicon based track microcavity resonator using finite-difference time-domain method

This paper presents an algorithm for use in designing a racetrack microresonator on silicon substrate, whose structure is illustrated. The accurate numerical FDTD has been used to calculate the characteristics of the device in the range of optical communication wavelengths. The optimum size of the guide, as well as the curvature of the curved guide, is considered from the results. From the optimum size of the device, the spectral response is consequently calculated, which leads to two important relationships between half-power bandwidth, HPBW, against the coupling efficiency, K, and free spatial range, FSR, against the racetrack round trip, X_rt. Having used these parameters of L and R, in conjunction with the optimum size of the guide, in FDTD simulation, the transfer characteristics can be obtained as following: X_rt = 17.94 μm, K = 0.223, FSR = 29.45 nm, HPBW= 4.45 nm, Q = 346.07 and finesse of 6.62, which are close to the design values. Therefore, our design procedure could be used in design of the dimensions of racetrack microresonators on silicon substrates in the communication wavelengths.