How Does a Polarization Beam Combiner Work?

About Polarization Beam Combiner

A polarization beam combiner is an important optical device that plays a key role in the fields of fiber optic communication, fiber optic sensing, fiber lasers, and optical amplifiers. A polarization beam combiner is an optical device capable of stably transmitting two orthogonal linearly polarized lights while maintaining their respective polarization states unchanged. It is mainly used for coupling, splitting, and multiplexing linearly polarized light to ensure that the optical signal maintains its polarization characteristics during transmission. The polarization beam combiner uses special structured optical fibers (such as polarization-maintaining fibers) and coupling technology to couple the optical signal transmitted in the fiber in the coupling area, redistributing the optical power. This coupling process can keep the polarization state of the optical signal unchanged, thereby achieving high-precision optical signal transmission and processing.

Features of MEISU's Miniature Polarization Beam Combiner 

MEISU's miniature polarization beam combiner adopts a compact packaging design, which is particularly suitable for Fiber Optic Gyroscopes (FOG). It can not only evenly distribute the input power like MEISU's ordinary PLC splitters but can also effectively maintain the polarization of the light beam. It uses waveguide chips and single-channel polarization-maintaining fiber arrays as input terminals, and dual-channel polarization-maintaining fiber arrays as output ports. It can effectively split the input power in half.

• Low insertion loss

  
  

• High return loss

  
  

• High extinction ratio

  
  

• Excellent environmental stability and reliability

  
  

• Ultra-compact size

Steps of Operation for Polarization Beam Combiner

Optical Signal Input

The optical signal enters the polarization beam combiner through the input port. These optical signals are usually linearly polarized light, and their polarization direction is roughly aligned with one of the principal axes (such as the fast axis or slow axis) of the polarization-maintaining fiber.

Polarization Maintaining Fiber Transmission

When the optical signal is transmitted in the polarization-maintaining fiber, due to the birefringence characteristics of the fiber, the two orthogonal polarization components of the optical signal will propagate along different paths (fast axis and slow axis), but their relative phase and polarization state will remain unchanged (or change very little).

Action of the Coupling Area

In the coupling area of the polarization beam combiner, the input optical signal is partially or entirely coupled to the output port through fusion tapering, waveguide coupling, or other special technologies. In this process, the coupler needs to precisely control the path and polarization state of the optical signal to ensure that the polarization characteristics and power distribution of the output optical signal meet the requirements.

Optical Signal Output

After passing through the coupling area, the optical signal is output from the output port. Depending on the design of the coupler, the output optical signal can be a direct coupled output of the original input optical signal or a signal processed through splitting, multiplexing, or other methods. It is important that the polarization state of the output optical signal should be consistent with the input optical signal (or adjusted as needed).