What Is an Optical Cavity?

A resonant cavity composed of two spherical mirrors with a common axis is called a coaxial spherical cavity; one of the mirrors (or both) is a special case of this type of cavity. When theoretically analyzing such a cavity, it is generally considered that there is no optical boundary on its side (an ideal processing method), so this type of cavity is called an open optical cavity, or open cavity for short ^[1]