The fiber array (or fiber array unit) is a one-dimensional or two-dimensional fiber array. Usually, such an array is formed only for the end of a bundle of fibers, rather than forming over the entire fiber length.
The purpose of such an array is usually to couple light from a source array to an optical fiber, or to couple light from an optical fiber to some other component, such as a planar waveguide array on a photonic integrated circuit.
It is usually formed by placing a single fiber in a V-shaped groove made on some solid surface. For example, precise hole arrays in glass or polymer sheets or metal plates can be used to achieve fiber positioning in a 2D fiber array.
Different types of 2D matrices can be used, but the most common is a simple square lattice. A simple and very regular structure is almost always formed, although more complex and less regular patterns are also possible.
For example, there is fiber array with multiple groups of fibers, that is, the spacing between some fibers increases. However, the truly irregular structures are called fiber bundles. The fiber bundle may also have a completely regular array at the end that serves as an interface, while at the other part, the fibers form an irregular bundle.
Generally, the fiber spacing is as small as possible, but in some cases, fiber arrays with much greater spacing are used for certain applications.