Optical Cavity with Large Operational Bandwidth using Silicon-Based Slotted Micromirrors

In this paper, we report FDTD simulations and experimental results of novel silicon-based optical microcavity comprising of two slotted micromirrors. While the normal range for silicon microcavities is limited by its absorption below 1.1 μm, we demonstrate a silicon cavity that is capable of operation from the visible spectrum till the telecom C-band. Deep reactive ion etching (DRIE) is used to fabricate the deeply etched microcavity mirrors. The structure is metallized with gold to enhance mirrors' reflectivity. The slotted mirror and the cavity structure are simulated using finite difference time domain (FDTD), and the results are reported showing a quality factor of 2796 for visible TM excitation and a quality factor of 2346 for NIR TM excitation. The experimental results report the characteristics of the resonator and verify its operation in the NIR and visible ranges. The measured quality factor (Q) is 2067 around the 565 nm peak and 1922 around the 1550 nm peak. Such a microcavity would present a major step towards realizing visible laser on silicon for micro optofluidic applications.