How to reduce fiber splicing loss.

What is fiber splicing loss? After the optical fiber is spliced, the light transmission to the joint will produce a certain amount of loss, which is called splicing loss or splicing loss.

Causes of loss: Fiber splice loss is mainly composed of the transmission loss of the fiber itself and the splice loss at the splice joint of the fiber. Since the quality of fiber optic splicing affects parameters such as the limit of transmission loss of fiber optic lines and the transmission distance of fiber optic lines without relay amplification, it is necessary to reduce the loss of fiber optic fusion splices as much as possible to ensure the transmission quality of fiber optic CATV signals.

The loss occurring in optical fiber communication is mainly composed of the transmission loss of the optical fiber itself and the fusion loss at the optical fiber joint. There are many factors affecting the fiber splicing loss, which are related to the fiber itself and on-site construction. Efforts to reduce the splicing loss at the fiber joint can increase the transmission distance of the fiber relay and increase the attenuation margin of the fiber link.

Fiber Splice Loss

It can be divided into two types: fiber intrinsic elements and extrinsic elements:

1. The intrinsic factors of the optical fiber refer to the factors of the optical fiber itself. There are four main points:

(1) The fiber mode field diameters are inconsistent;

(2) The core diameters of the two optical fibers are mismatched;

(3) The fiber core is not round;

(4) The concentricity between the core and the cladding is not good.

Among them, the difference in fiber mode field diameter has the greatest impact. According to the recommendation of CCITT (International Telegraph and Telephone Consultation Committee), the tolerance specification of single-mode fiber is as follows:

Mode field diameter: (9——10μm)±10%, that is, the tolerance is about ±1μm;

Cladding diameter: 125±3μm;

Mode field concentricity error ≤ 6%, cladding out-of-roundness ≤ 2%.

The extrinsic factors that affect the fiber splicing loss are the splicing skills:

(1) Axis misalignment: The core of a single-mode fiber is very thin, and the misalignment of the axes of two butt-connected optical fibers will affect the splice loss. When the misalignment is 1.2μm, the connection loss reaches 0.5dB.

(2) Axis tilt: When the fiber section is tilted by 1°, about 0.6dB splice loss occurs. If the splice loss is required to be ≤0.1dB, the inclination angle of the single-mode fiber should be ≤0.3°.

(3) End-face separation: The connection of the moving connector is not good, and the end-face separation is easy to occur, resulting in a large connection loss. When the discharge voltage of the fusion splicer is low, end-face separation is also prone to occur. This situation can generally be found in fusion splicers with tensile test functions.

(4) End face quality: When the flatness of the end face of the optical fiber is poor, loss or even air bubbles will occur.

(5) Physical deformation of the optical fiber adjacent to the fusion point:

The tensile deformation of the optical cable during the erection process, the excessive pressure of the optical cable clamped in the fusion splice box, etc., will affect the splice loss.

Influence of other elements:

Splicing personnel's operation level, operation pace, fiber coil process level, electrode cleanliness in the fusion splicer, welding parameter settings, and cleanliness of the working environment will all affect the value of the splice loss.

2. What are the methods to reduce the loss of optical fiber splicing

Try to use uniform batches of high-quality brand-name bare fibers on one line

Cable erection is carried out as required

Select experienced and well-trained optical fiber fusion splicing personnel for fusion splicing

At present, most of the fusion splicing is automatic fusion splicing machine, but the level of splicing personnel directly affects the size of splicing loss. Splicing personnel should perform splicing in strict accordance with the optical fiber fusion splicing process flow chart, and during the splicing process, they should use OTDR to test the splicing loss of the splicing point while splicing.

Those that do not meet the requirements should be re-spliced. For the point with a large value of splice loss, it is advisable to repeat the splice times 3-4 times.