A fiber coupler or fiber optic coupler is a device used in optical fiber system with one or multiple input fibers and one or several output fibers. The power distribution is dependent on the wavelength and polarization as the light is entering an input fiber. These couplers can be fabricated in different ways like thermally fusing fibers. There are also couplers that can combine two inputs at different wavelengths into one output without any loss. It is mainly used in wavelength-division multiplexing (WDM) telecom systems to combine the several input channels.
Polarization maintaining fiber coupler is capable of combining two or more inputs into a single output and also divides a single input into two or more outputs. The fused coupler is developed using fusing technique and polarization maintaining fiber. Certain applications for PM couplers include optical sensors, optical amplifiers, and fiber gyroscopes. They are more useful in optical communication & transmission and is available in different configuration of 1×2, 2×2, 1×3 (monolithic) and 1×4 (compact cascaded).
Features and characteristics of PM fiber coupler
- It incorporates Low Insertion Loss
- It has high extinction ratio
- Available in compact In-Line Package
- It enables high stability and reliability
- It maintains good uniformity with high directivity
- Wide variety of wavelengths 780 nm-2005 nm
- It is used for fiber optic instruments and fiber sensors
- It is also used in research works and enables coherent detection
They provide an improved PER (≥20 dB including connectors) and a wide -40 °C to 85 °C operating range. The couplers undergo extensive testing and verification of the PER and they are available with 2.0 mm narrow key FC/PC and FC/PC connectors. The IL will be 0.3dB higher and RL will be 5 dB for devices with connectors. The extinction ratio is also specified in the same way and they are aligned to the slow axis of the fiber. They are available in compact packaging options and it is advisable to contact the companies who specialize in the manufacturing of PM Fiber Coupler.