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The Working Principles of MEMS Optical Switches

Optical switch is one of the core devices for realizing functions such as optical cross connection, optical add/drop multiplexing, network monitoring and optical line protection. It converts optical signals from one optical channel to another within a certain range, with one or multiple selectable transmission windows.

What is a MEMS Optical Switch?

Based on its switching technology, there are diverse types of optical switches, including mechanical optical switch, thermal-optic switch, acousto-optic switch, magneto optical switch, liquid crystal optical switch, MEMS optical switch, etc. Traditional switches with electricity as the core technology gradually lag behind the demand for high speed and large capacity optical communication, which gave rise to all-optical switches in the market. Among them, MEMS optical switches are widely used featuring compact size, low power consumption and good expansibility.

Working Principles of MEMS Optical Switches

MEMS (Micro-Electro-Mechanical System) is a micro device or system integrating micro-machinery, micro-actuator, signal processing and control circuits, etc. Micro-mechanical structures are prepared by photo-lithography, ion beam etching, chemical etching, wafer bonding, etc., while electrodes are prepared on the mechanical structure for electronic control.

MEMS is a micro-motor system that needs to be driven electronically after the preparation of a micro-mechanical structure. Typical driving mechanisms include electrostatic attraction, electromagnetic force, electrostriction and thermocouple. Among all the driving mechanisms of MEMS devices, electrostatic gravitation structure is widely used due to its simplicity of preparation, easy control and low power consumption.

A MEMS optical switch is to engrave a number of tiny lenses on silicon crystal, and rotate the micro mirror array through the action of electrostatic force or electromagnetic force, so as to change the propagation direction of the input light to realize the function of optical path on and off.
Generally speaking, MEMS optical switches can be divided into two types based on the spatial structure, namely 2D switch and 3D switch.

Structure of MEMS Optical Switches

Optical switch is a multi-port optical device, with common port configuration such as 2×2, 1×N, N×N. Among them, the N×N optical switches are also called OXC (Optical Cross Connection) switches. 1×N MEMS optical switch includes a MEMS micro mirror, a collimating lens, and a multi-fiber pigtail. The MEMS micro mirror is usually mounted on a TO holder, and then the collimating lens and the TO base are assembled into a sub-assembly by means of the TO cap. Finally, the multi-fiber pigtails are aligned and fixed to the above sub-assembly under active commissioning.

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Printed on: June 13, 2024 at 16:06 o'clock