Determination of bandwidth and free spectral range for the silicon based ring resonators and racetrack microcavity resonators

This paper determines the free spectral range, FSR, and the half-power bandwidth, HPBW, of the racetrack microresonator, RTM, against the ring microresonator, RM, on silicon substrate. The accurate numerical FDTD has been used to calculate its characteristics in optical communication wavelengths. At the optimum size of the device, the spectral response is calculated, which leads to two relationships between HPBW against the coupling efficiency and FSR against the racetrack round trip. These relationships can be used to determine the possibly maximum FSR and the least HPBW for the RM. Both parameters are degraded for the high coupling RTM.