Principle of optical fiber coupler

Optical network systems need optical coupling of the signal, branch, also need to be allocated, this requires optical fiber coupler to achieve. Fiber Coupler, also known as optical splitters, optical Distributor, is the most important passive fiber links one of the devices which was with multiple input and multiple output terminals optical fiber tandem devices, MxN commonly is used to indicate a tap which has M inputs and N outputs. Optical splitter for use in optical fiber CATV systems are generally composed of 1x2, 1x3, as well as by their 1xN fiber optic splitter Principle.

It Can be divided into fused biconical taper and Planar waveguide type two, fused biconical taper-friendly products is to combine two or more sides formed by the fusion of fiber; Planar waveguide type is micro-optical components products, the use of lithography, in the media or form of optical waveguide on semiconductor substrate, branch distribution function. The two types of light on a similar principle, has gone between them by changing the optical fiber coupling (coupling, coupling length), as well as changing the radius of optical fiber to achieve different sized branches and vice versa can also multiplex optical signal into a signal called a synthesizer.

Fused-taper fiber couplers by making method is simple, inexpensive, easy to connect to external fibre as a whole, and resistance info-mechanical vibration and temperature changes, and other advantages, is now mainstream manufacturing technologies Shenzhen Flach factory's products.

common specifications
(1) the insertion loss. Insertion loss optical splitter are each number of dB loss of output relative to the input light, its mathematical expression is: Ai=-10lg Pouti/Pin, where Ai is the I-th outlet insertion loss Pouti is the I-th output optical power; Pin was input optical power value.

(2) additional loss. Additional loss is defined as the total of all optical power output port number of DB relative to the input optical power loss.

It is worth mentioning that, for Optical Fiber Coupler, additional losses are reflecting device manufacturing process quality indicators, reflects the inherent loss of their manufacturing process, the wear and the smaller the better ,it is to produce quality assessment index. Insertion loss is only output power of each output port situation, not only has the inherent loss factor, considering the impact of a ratio. Between different optical fiber Coupler, differences do not reflect device insertion loss making quality is good or bad. 1*N standard single-mode fiber optic splitter additional loss as shown in the following table: Tap: 2 3 4 5 6 7 8 9 10 11 12 Additional loss DB 0.2 0.3 0.4 0.5, 0.55 0.6 0.7 0.8 1 1.2

(3) the dividing ratio. Min light than defined for light tap Manager the output port of output power ratio, in system application, min light than indeed is according to actual system light node by need of light power of quantity, it determines suitable of min light than (average distribution of except), light tap Manager of min light than and transmission light of wavelength related, such as a light tap in transmission 1.31 Micron of light Shi two output end of min light than for 50:50 ; When transmitted light 1.5 μ m, becomes 70:30 (such a situation occurs, it is because optical splitter has a certain amount of bandwidth, which means that transmission of optical signals when the ratio is essentially the same bandwidth). So when Shenzhen Flach company provides fiber optic splitter, it must indicate the wavelength.

(4) degree of isolation. Isolation refers to the light taps one of the optical signal in the optical path to other optical isolation. In these indicators, isolation for optical splitter is more significant, in a real system application, it often requires isolation of 40dB or more devices, it will affect the performance of the system as a whole.

Stability is also an important indicator of optical splitter, the so-called stability refers to the outside temperature changes, when the work of the other device state changes, fiber optic splitter ratio and other performance indicators should remain unchanged, in addition, uniformity, return loss, directional and PDL all optical splitter occupies a very important position in the performance indicators. Shenzhen Flach company is a good solution to such problems.