How to use fiber optic coupler

Optical fiber coupler (Coupler), also known as splitter (Splitter), connector, adapter, optical fiber flange, is a component used to realize optical signal splitting/combining, or used to extend optical fiber links, belonging to optical passive components In the field of telecommunication network, cable television network, user loop system, local area network will be applied.

Single Mode Fiber Couplers

Single-mode fiber couplers are the most widely used. 2&TImes;2 single-mode fiber coupler is typical, and its composition is shown in the figure. It has two inputs and two outputs with a coupling section in between. Figure 2(a) is made by melt stretching process. The stretched portion forms a tapered coupling region.

Stretching expands the optical energy in the core region to the outside of the core; at the same time, the two cores are brought closer to each other, both of which enhance the coupling. The optical signal input by 1 or 2 is distributed through the tapered coupling area and output by the 3 and 4 terminals. The proportion of distribution is called the coupling ratio and is controlled by the length of the stretch zone. In the figure (b), the cladding of the optical fiber embedded in the quartz block with a certain curvature is removed by the grinding and polishing method, and then two such quartz blocks are pressed together so that the two fiber cores are close to each other to form an optical fiber coupler.

The coupling ratio is determined by the proximity of the core and the radius of curvature of the fiber in the silica block. The coupling ratio can be selected from 1% to 99%, and the insertion loss is less than 0.5dB. The optical signal coupled out of the input light in the opposite direction is extremely weak, so the fiber coupler is often called a directional coupler.

Multimode Fiber Couplers

The principle and structure of the multimode fiber coupler are basically similar to the above, except that the grinding and polishing device requires strong coupling, so the grinding and polishing plane enters the fiber core. On the basis of grinding and polishing type 2&TImes;2 fiber optic couplers, adjustable couplers can also be made. At a certain wavelength, the coupling ratio changes with the angle formed by the two polished fibers, so the coupling ratio can be changed by adjusting the relative directions of the two fibers.

L&TImes;N, N&TImes;1 couplers or N×M couplers (or star couplers) are also used in optical fiber local networks or other occasions, where the first number represents the number of input terminals, and the second number represents the number of output terminals. These couplers are made by fusion pull method.

The role of fiber optic couplers

The optocoupler consists of two parts: a light source and a light receiver. The light-emitting source and the light-receiver are assembled in the same closed casing, and are isolated from each other by a transparent insulator. The pin of the light-emitting source is the input end, and the pin of the light receiver is the output end.

The function of optical fiber couplers is to realize optical signal splitting/combining, or components used to extend optical fiber links. applicable to.

Instructions

In use, two lengths of fiber optic lines are connected to the two ports of the fiber optic coupler, and then combined together. Different types of fiber optic couplers have different forms and are mainly based on specific products.

Classification

According to the difference of the coupled fibers, they are classified as follows:

SC fiber optic coupler: applied to SC fiber optic interface, it looks very similar to RJ-45 interface, but SC interface is flatter, the obvious difference is the contacts inside, if it is 8 thin copper contacts, then It is an RJ-45 interface, and if it is a copper column, it is an SC fiber interface.

LC fiber optic coupler: A connector used in LC fiber optic interfaces to connect SFP modules, it is made with a modular jack (RJ) latch mechanism that is easy to operate. (commonly used by routers)

FC fiber optic coupler: applied to FC fiber optic interface, the external strengthening method is a metal sleeve, and the fastening method is a turnbuckle. Generally used on the ODF side (the most used on the patch panel)

ST fiber optic coupler: used in ST fiber optic interface, commonly used in fiber optic distribution frame, the outer shell is round, and the fastening method is turnbuckle. (For 10Base-F connections, the connectors are usually ST type. Often used in fiber optic distribution frames)