A Brief Guide on the Need and Use of Inline Polarizers

The need for efficient low-loss components that are compatible with optical fibers is growing quickly. An all-fiber inline polarizer is therefore a more desirable alternative that can be placed at appropriate intervals along communication links. It works by coupling optical energy traveling in the fiber to a surface Plasmon on a metallic film, which is deposited to the surface of the fiber.

What is polarization and why does polarization of light matter?

Polarization is a special property of electromagnetic waves that refers to the behavior of the electric field with time. If the electric vectors of a group of transverse waves (longitudinal waves cannot be polarized) are at random angles (i.e. in all or any directions), a light is said to be unpolarized. If the electric vectors of transverse waves have the same angles, the light is said to be polarized.

Polarization is desirable in many components and systems because the use of unpolarized light leads to interference and performance issues. 

Fiber optics components such as polarizers transmit waves with electric vectors in one plane and the other waves are either reflected or absorbed.

The operational characteristics of many fiber optic systems vary by the polarization of the light travelling in the optical fiber. That is why maintaining polarization is essential in fiber optics communications, optical gyroscopes, and interferometric sensors to prevent signal fading and error.

To obtain a high level of accuracy in measurements, it is important to have the light with just one polarization. Therefore, it is crucial to implement fiber optic polarizers with a high extinction ratio.

Why use in-line polarizers instead of standard polarizers?

Standard polarizing components in optical systems are bulky, which makes it difficult to align the optical axis between components. Besides, using bulky polarizers can result in higher costs, lack of mechanical and thermal stability, and high losses.

Hence, when it comes to maintaining the polarization of the light in the fiber, the most desirable fiber optic component is an in-line polarizer because it has a fiber-like structure, making it easier to align the optical axis between components.

Inline fiber components are more desirable in most fiber optics systems and have been successfully used in beam splitters, faraday rotators, and filters.

What are the different types of fiber polarizers?

The first optical polarizer was made using calcite prism. However, because of the limitations posed by the optical constants of calcite crystal, it was soon replaced by dichroic polarizers. If natural light falls on some homogeneous media and the light is partially polarized either circularly or linearly, such media are called dichroic.

The commercial usefulness and viability of fiber inline polarizers depend on several key aspects of the construction and design.

At DK Photonics, we offer a wide range of fiber polarizers, such as 980nm in-line polarizers, 1030nm in-line polarizers, 1064nm in-line polarizers, 1480nm in-line polarizers, 1550nm in-line polarizers, 2000nm in-line polarizers, 2050nm in-line polarizers, and more.