Optical resonators are devices that are used in optics and photonics to enhance the interaction between light and matter. They consist of a cavity or resonator structure that is designed to trap light and allow it to interact with the surrounding material. This enhances the intensity of light within the resonator, leading to effects such as increased absorption, emission, or amplification of light. Optical resonators are used in a wide range of applications, including lasers, optical filters, sensors, and optical modulators. They can be constructed using a variety of materials and structures, such as microcavities, photonic crystals, and whispering-gallery resonators. Overall, optical resonators play a vital role in enabling the manipulation and control of light in various optical and photonic devices, making them an important research area in the field of optics and photonics.