Optical switches are used to perform ON/OFF operations or reroute a fiber optic signal.All kinds of telecommunication network need switches, so is the fiber optic network. Optical switch is a vital part in the fiber optic systems.

First we discuss about the simple models of optical switch. The simplest one, 1X1 optical switch.
This switch either allows or stops the fiber optic signal to pass it. 1X2 switch has an input port (for example port 1) at one side and two output ports at the other side (for example port 2 and port 3), 1X2 optical switch could reroute the light from port 1 to go through port 2 or port 3. 1XN types switches are commercially available nowadays.2X2 switches is a little complicated, it can connect two fiber with other two fibers, the 2X2 optical switches are used for node by passing in fiber optic systems like in FDDI networks.

Main parameters of the fiber optical switch include extinction ratio, it is the ratio of light power of the on state to the off state position of the switch. This is the characteristic for ON/OFF switch. Insertion loss means the power lost due to the presence of optical switches. Crosstalk is the ratio of the output power generated by the desired input to the output power generated by undesired inputs. Switching time is the most important parameter, as is true for tunable filters, switching time depends on the switch’s applications.

There is a complicated MXN configuration fiber optical switch, such a switch matrix or arrays could be found to use in WDM systems, they are actually combination of the simple models switches in multistage structure.

Modulized optical switch is a switch which enable user to customize its function using different modules.When plugged with different modules they could function to be diffrent type switches, such as 1X2,1X4,1X8 and 2X2,providing highly flexible routing of optical signals.