Optical couplers are used to

Optical couplers are devices that split or combine optical signals between two or more fibers, enabling efficient signal distribution in fiber optic systems.Definition and FunctionAn optical coupler is a device used to transfer light from one or more input fibers to one or more output fibers. It can either split a single input signal into multiple outputs or combine multiple input signals into a single output. This allows optical signals to be distributed, merged, or tapped for monitoring purposes in optical networks and communication systems . Couplers are typically directional, meaning light entering an input port does not return to the same port .Types of Optical CouplersOptical couplers can be categorized based on their structure and function:Fiber Optic Splitters: Devices with one input and multiple outputs, such as Y-couplers or T-couplers, which divide the input signal equally or unequally .Optical Combiners: Devices with multiple inputs and a single output, used to merge signals from different fibers .Directional Couplers: Standard couplers like 2x2 or star couplers that distribute signals among multiple ports .Specialized Couplers: Include Fused Biconic Taper (FBT) couplers, Planar Lightwave Circuit (PLC) couplers, and Wavelength Division Multiplexing (WDM) couplers, each designed for specific applications .Working PrinciplesOptical couplers operate by redistributing optical power. In a fused fiber coupler, for example, two fibers are fused and tapered so that a fraction of the light from one fiber is transferred to the other. The coupling ratio defines the proportion of power distributed to each output port and can be wavelength-dependent or independent . Passive couplers require no external power, while active couplers use detectors and light sources to manage signal transmission .ApplicationsOptical couplers are widely used in:Optical communication networks for signal splitting, combining, and monitoring.Fiber optic measurement and testing to tap signals without interrupting the main transmission.Multiplexing and demultiplexing in WDM systems to combine or separate different wavelength channels . In summary, optical couplers are essential components in fiber optic systems, enabling flexible and efficient management of optical signals across multiple fibers.