An optical cavity is a space where light is confined between two or more reflective surfaces, such as mirrors. This setup allows light to bounce back and forth, enhancing its intensity. Optical cavities are essential components in devices like lasers, where they help produce coherent light. The design of an optical cavity can vary, but it typically includes a gain medium, which amplifies the light. The quality of the mirrors and the alignment of the cavity significantly affect its performance. Applications of optical cavities extend to telecommunications, spectroscopy, and various scientific instruments.