The Working Principle and Application of MEMS Optical Switch

An optical switch is a component that can switch an optical signal from one optical channel to another within a certain range. There are one or more transmission windows that can be selected, so as to better realize optical cross-connection and so on. MEMS is a micro-motor system that can be driven by electronic technology behind the mechanical structure of the paper cup. The more common ones include electrostatic attraction, electromagnetic force and so on. Then MEMS optical switch is a device based on micro-electro mechanical system to realize optical path switching.

Working Principle
The MEMS optical switch is to engrave a number of tiny mirrors on the silicon crystal, and through the action of electrostatic force or electromagnetic force, the micro mirror array is rotated, thereby changing the propagation direction of the input light to realize the function of on-off of the optical path. The MEMS optical switch switches the light wave route through external control information and corresponding high and low levels to control whether the internal micro lens is lifted or not.

Generally, MEMS optical switches are classified in terms of spatial structure into 2D optical switches and 3D optical switches. Then the working principles of the two types are different.

The space rotating mirror of 2D MEMS is monolithically integrated on the silicon substrate through the surface micromachining technology, and the collimated light is connected to the designated output end through the rotation control of the micro mirror. When the micro mirror is horizontal, the light beam can pass through the micro mirror. When the micro mirror is rotated to be perpendicular to the silicon substrate, it will reflect the incident light beam on its surface, so that the light beam will pass through the output port of micro mirror.

In the 3D MEMS optical switch, the micro mirror can be rotated at any angle along two axes, so it can change the output of the optical path at different angles. These arrays usually come in pairs, with input light arriving on the mirror of the first array being reflected on the mirror of the second array, and then reflected on the output port.

Applications
With the continuous development of optoelectronic communication, MEMS optical switches are also widely used in many industries. It is mainly used in the protection switching system of optical network, the light source control system, including optical device test and building the switching core of OXC equipment, optical add/drop multiplexing, optical testing, and optical sensing systems.

Optical performance monitoring
Integrate with TOF or OPM to combine with monitoring software, and monitor the signal performance of DWDM channels in multi-core optical fibers through time division multiplexing OPM. It can be widely used in optical transmission network optical cable monitoring, ROADM network, DCI, etc.

Optical cable monitoring
Integrated with OTDR and combined with monitoring software, it monitors the quality status of multi-core optical fibers in optical cables through time division multiplexing of OTDR. It is widely used for PON network fiber optic cable monitoring, optical transmission network optical cable monitoring, industry specific network fiber optic cable monitoring, etc.