Fiber Collimators

Fiber Collimator made of stainless steel; size: ∅6.81mm x 9.27mm

A fiber collimator is an optical component designed to transform the light emitted by an optical fiber into a collimated beam with a specified diameter or a designated spot size. When used in reverse, it can also focus light into a fiber. At Shanghai Optics, we produce a wide range of custom, high-quality fiber optic collimators with various focal lengths and aperture sizes. Our fiber collimators can be used for funneling light in and out of SMA, FC/APC, or FC/PC terminated fibers. They are compatible with single-mode, multi-mode, and polarization-maintaining fiber and can be used for applications in communications and data transfer, with pigtailed receptacles or fiber-coupled lasers.

Our fiber collimators are diffraction-limited, enabling very small spot sizes and beam diameters. Antireflection coatings on the component lenses minimize back reflection. Our collimators feature an extensive operating distance, have low insertion loss, and are easy to integrate into existing systems. State-of-the-art metrology allows us to ensure that each fiber collimator performs stably and optimally in its intended application.

Understanding Fiber Optic Collimators

Light emitted directly from an optical fiber forms a cone of illumination, with a divergence angle approximately equal to the input angle. To produce beam-like outputs, a fiber optic collimator can be used to collimate the light, creating a beam with parallel rays and minimal spread.

At its most basic, a fiber collimator consists of a lens and an optical fiber, housed in stainless steel with appropriate fiber connectors. The mechanical connectors enable the collimator to be easily attached to or removed from a connectorized fiber. 

The type of lens and the exact configuration of the collimator depend on the application in which it will be used. Most fiber collimators today utilize Graded Index (GRIN) lenses, small optics with plane surfaces that focus light through the continuous change of refractive index within the lens material itself. For larger beam sizes (1 mm to 5 mm), aspherical lenses may be used to focus the light. Spherical singlet or doublet lenses are often selected when a beam size greater than 4 or 5 mm is needed. These fiber collimators are larger in size than those for smaller beam sizes. Note that the relative mode size of the fiber and beam size are not the same; in fact, a smaller fiber mode size will result in greater divergence and larger collimated beams. Additionally, collimator performance is inherently influenced by the laser’s mode field distribution.

Two fiber collimators can be used as a pair to couple light from one fiber to another through a free-space beam. The first collimator transforms the diverging light output of the first fiber into a collimated free-space beam with a nearly constant diameter. The second collimator then receives this beam and couples the light into the second fiber. As with any coupling, careful alignment and stabilization are key to minimizing power loss.  

Fiber Optic Collimators at Shanghai Optics

We can work with you to customize the perfect solution for your application. Contact us if you’d like more information or a free consultation.