Inverse design of all-dielectric parallel-plane mirror optical resonator

Inverse-design algorithms can be used to design compact and high-performance complex photonic structures. In this study, we propose the design of an all-dielectric optical resonator based on the concept of the parallel mirror resonator by using the objective-first inverse design algorithm. Light is strongly confined using a predefined objective function that creates symmetric mirror regions acting as reflective layers for the fundamental transverse-electric polarization mode. Thanks to the flexibility of the algorithm, segments of the cavity and dielectric mirror are designed in a simulation region by choosing a cavity of an appropriate length. A time-domain analysis of the proposed structure was carried out using the two-dimensional finite-difference time-domain method. The proposed structure has a configuration with a footprint of 13.394 x 0.592 mu m(2). The algorithm generates an inverse-designed structure to obtain a resonance peak at the target wavelength without any intuitive scanning of the complete parameter space. As a result, the first-order mode is strongly localized in the region of the cavity for the defined design wavelength. Moreover, the application of the inversely designed resonator as refractive index sensor is examined to show that the proposed structure has the potential for use in integrated photonic devices. Thus, the objective-first inverse design algorithm is promising for use in the design of a variety of photonic structures.