Fiber coupler (Coupler) is also known as the differences (Splitter), connectors, adapters, flange, is used to implement the optical signal splitter / combiner, or for extending fiber link elements belonging to the field of optical passive components in telecommunications networks, cable television networks, subscriber loop system will be applied to the local area network. Fiber coupler can be divided into standard coupler (part of the waveguide, dual branch unit 1 × 2, ie the optical signal into two power), direct attach coupler (connected to the same or different types of fiber optical interface 2 to extend fiber link), star / tree couplers, and wavelength division multiplexer (WDM, if the wavelength is a high-density separation, ie a narrow wavelength spacing, belongs DWDM), production methods, there are sintering (Fuse), micro optical (Micro Optics), an optical waveguide type (Wave Guide) three, and sintered produced the majority (about 90%). Sintering method making method is to burn together two optical fibers and melt tension, so that the core polymerization together to achieve light coupling, and one of the most important production equipment is an optical fiber welding machine, which is an important step, although an important step by the machine OEM part, but after sintering, people still work detection package, so labor costs account for about 10 to 15%, furthermore using manual inspection package must guarantee the consistency of quality, and this is when mass production It must be overcome, but the technical difficulty is not as DWDM optical modules and active components is high, and therefore would like to enter the initial fiber industry manufacturers, most of them will cut from the optical coupler, the gross margin of 20% to 30.

  Single-mode fiber coupler most widely used. 2 × 2 single-mode fiber coupler is typical, as shown in its composition. It has two inputs and two outputs, the middle section of the coupling region. Figure 2 (a) is produced using melt drawing process. Stretching portion tapered coupling region. Stretching the core region to make energy outside the core extension; the same time, so that the two cores close to each other, these two effects are enhanced coupling. 1 or 2 by the optical signal input, distribution through a tapered coupling region, 3 and 4 by the end of the output. Prorated called coupling ratio, by the length of the stretching zone control. FIG. (B) show a method of grinding and polishing using a curvature quartz block embedded fiber cladding removed portion, so that the two quartz pieces and then snapping the core so that the two approach each other to form a fiber coupler. Coupling ratio determines the degree of curvature radius near the optical fiber and the quartz block by the core. Coupling ratio can be between 1% to 99% is selected, the insertion loss is less than 0.5dB. Input light is coupled out of the optical signal in the opposite direction very weak, it is often referred to as a fiber coupler directional coupler.

  The principle and structure of multi-mode fiber coupler is substantially similar to those described above, except that grinding and polishing type device requires strong coupling effect, it is grinding and polishing the plane into the core. In the grinding and polishing type 2 × 2 optical fiber coupler based on, you can also make adjustable coupler. In certain wavelength, the coupling ratio with two grinding and polishing optical fiber at an angle changes, so adjusting the relative orientation of the two fibers can change the coupling ratio.

  In the optical fiber local network or on other occasions also uses l × N, N × 1 coupler or N × M coupler (or star coupler), where the first number represents the number of inputs, the second number represents the number of output terminals. These couplers are used in the production of melt-drawing method.

  According to different fiber coupling are classified as follows:

  SC fiber optic coupler: SC fiber interface is applied to it with RJ-45 interface looks very similar, but SC interface seems more flat some, the obvious difference inside the contact sheet or, if it is 8 thin copper contacts, the it is the RJ-45 interface, if it is a copper cylinder is SC fiber interface.

  LC fiber coupler: used LC fiber interface, SFP module connector connector, which uses easy to operate modular jack made (RJ) latch mechanism. (Routers commonly used)

  FC fiber optic coupler: FC applied to optical fiber interface, external to strengthen the way is to use a metal sleeve, fastening means for the turnbuckle. Generally adopt ODF side (with the patch panel Up)

  ST fiber coupler: used ST fiber interface, commonly used in fiber optic patch panels, rounded shell, fastening means for the turnbuckle. (For 10Base-F connections, usually ST type connectors commonly used in optical fiber distribution frame)