A resonant cavity component can be used in an optical switching system, and includes a resonant cavity group, where the resonant cavity group includes at least two resonant cavities that have displacement in a vertical direction, and adjacent resonant cavities exchange optical energy by means of evanescent wave coupling; a restriction layer between resonant cavities that has a relatively low refractive index; and at least one optical waveguide, close to a bottom-layer resonant cavity in the resonant cavity group, couples optical energy, and is used to input or output an optical signal. In implementation manners of the present invention, multiple resonant cavities have displacement in a vertical direction, are located in different planes, and may be made by using a CMOS process; and a space in a vertical direction can be controlled to a level of several nanometers.