What are Fiber Optic Switches?

Fiber Optic Switches are control devices used to redirect or guide light along the desired optical channels or paths in an optical fiber network to send data to the client address. It automates the connection from the incoming optical fiber to selected output optical fibers and hence eliminates the need to manually move fibers. Some optical switches also allow bidirectional connections.

Optical communication networks usually have multiple pathways to ensure that communication is not interrupted even during maintenance works. Optical switches can ensure that data signals are redirected to working communication pathways in a short time span of a few milliseconds. Also, optical switches can guide optical signals to various available communications pathways to reduce the workload of each fiber and to ensure large-volume data communications.

Optical Switches can be classified into two: All-optical switches and electrical conversion optical switches.

All-optical switches maintain the signal in the optical domain during the switching process which ensures faster and more reliable optical switching as if both fibers were directly connected to each other and maintains high-speed optical communication. While the electrical conversion optical switches convert the input optical signals to electrical signals followed by conversion back to optical signals during the switching process. This affects the communication speed.

The optical signal received at an optical switch is directed to their corresponding output optical fibers based on the input control signals. 

Fiber optical switches utilize a variety of technologies from optomechanical to MEMS to solid-state optical switching.

Optomechanical switches use actuators to move optical components like mirrors or prism to redirect the optical signals to the selected output optical fibers as shown in the above figure. These are only used in small-scale devices as the presence of moving parts makes miniaturization difficult and limits simultaneous switching. Optomechanical switches are widely deployed as they were the first to be introduced.

In a MEMS optical switch, the angular orientations of each micro-mirror in a MEMS matrix are precisely adjusted based on the control signals such that the optical signal from each input fiber after reflection enters the corresponding output fiber. They use latches to preserve the mirror orientation for the required time period for which the signal should be guided to the selected output fiber. MEMS switches are miniature in size due to special fabrication methods employed including photolithography and etching.

Add/Drop multiplexer using optical switches

Fiber optic switches can be used to implement Add/Drop multiplexer in which an optical device or signal is added to or dropped from the optical network or system. As shown in the above figure, the inserted state allows the device/signal connected to the Add port to be routed/added to the network while and bypass state drops it.

Fiber optical switches are key components for various applications such as optical network monitoring, quantum photonics, secure switching, fiber optic sensing, components testing & measurement, and optical signal routing.

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