In optical fiber communication systems, optical switches (Optical Switch, OS) are mainly used to achieve physical switching of optical signals or other logical operations in the optical path, and are mostly used in optical cross-connect (OXC) technology as a key device for switching optical paths. The optical switch has one or more selectable transmission windows, which can be divided into 2×2, 1×N, M×N multiple port configuration forms. Optical switches have a wide range of applications in optical fiber communication systems, and their implementation technologies are diverse, including: mechanical optical switches, thermo-optical switches, acousto-optical switches, electro-optical switches, magneto-optical switches, liquid crystal optical switches and MEMS optical switches, etc.
Among them, mechanical optical switches and MEMS optical switches are two widely used optical switches. The working principle of the mechanical optical switch is to redirect the optical signal by physically moving the optical fiber with the aid of a mechanical device.
By moving the prism or directional coupler, the light at the input end is directed to the desired output port. There are three main types of mechanical optical switches: one is to use prism to switch the optical path technology, the other is to use mirror switching technology, and the third is to switch the optical path by moving optical fibers. The MEMS optical switch is based on a micro-electro-mechanical system, which uses an optical micro-mirror or an optical micro-mirror array to change the direction of the light beam to switch the light path.
The principle of the MEMS optical switch is very simple. When the light is exchanged, the angle of the MEMS micromirror is moved or changed by the drive of electrostatic force or magnetic power, and the input light is switched to the different output terminals of the optical switch to realize the switching and on-off of the optical path.
With the rapid development of optical communications, the status of optical interconnection and optical switching as optical network nodes is becoming more and more important, and the application of optical switches is becoming more and more extensive.
MEMS optical switches have the advantages of compactness, fast switching speed, and easy expansion. At the same time, they have the low insertion loss, low crosstalk, low polarization sensitivity, high extinction ratio and high switching speed of waveguide switches, small size, and easy expansion of mechanical optical switches. The advantages of large-scale integration. Will be the mainstream direction of the development of high-capacity switching optical network switches.
