When light is transmitted in an optical fiber, a loss will occur, and this loss is mainly composed of the transmission loss of the optical fiber itself and the splice loss at the optical fiber joint. Once the optical cable is ordered, the transmission loss of the optical fiber itself is basically determined, and the splice loss at the optical fiber joint is related to the optical fiber itself and on-site construction. Efforts to reduce the splice loss at the optical fiber joint can increase the optical fiber relay amplification transmission distance and improve the attenuation margin of the optical fiber link.
Fiber splice loss
Main Factors Affecting Fiber Splice Loss
There are many factors that affect the loss of optical fiber fusion, which can be roughly divided into two categories: intrinsic factors and extrinsic factors of optical fibers.
1. The intrinsic factor of the fiber refers to the factor of the fiber itself, and there are four main points.
(1) The fiber mode field diameter is inconsistent;
(2) The core diameters of the two optical fibers are mismatched;
(3) The core section is not round;
(4) The concentricity between the core and the cladding is not good.
Among them, the inconsistency of fiber mode field diameter has the greatest impact. According to the recommendation of CCITT (Consultation Committee for International Telegraph and Telephone), the tolerance standard 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%.
2. The extrinsic factor that affects the optical fiber splice loss is the splice technology.
(1) Axial misalignment: The single-mode fiber core is very thin, and the axial misalignment of two butt-jointed fibers will affect the splice loss. When the misalignment is 1.2μm, the splicing loss reaches 0.5dB.
(2) Inclination of the axis: When the optical fiber section is inclined by 1°, a splice loss of about 0.6dB is generated. 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 movable connector is not good, and it is easy to cause end face separation, resulting in large connection loss. When the discharge voltage of the fusion splicer is low, end face separation is also likely to occur, which can generally be found in fusion splicers with a tensile test function.
(4) End face quality: When the flatness of the fiber end face is poor, loss and even air bubbles will occur.
(5) Physical deformation of the optical fiber near the splice point: the tensile deformation of the optical cable during the erection process, and the pressure of clamping the optical cable in the splice box is too large, which will affect the splice loss, and even several times of fusion can not be improved.
The influence of other factors, the operation level of the splicer, the operation steps, the fiber coil process level, the cleanliness of the electrodes in the fusion splicer, the settings of the fusion parameters, and the cleanliness of the working environment will all affect the value of the fusion loss.
