|Loss in fiber optic|
Optical fiber test for transmissionBefore using optical fiber for transmission, we have to get information related to losses. Before using optical fiber for transmission, we have to get information related to losses. Below are the main measurements implemented on optical fibers.
➤End-to-End Optical Link Loss
➤Rate of attenuation per unit length
➤Attenuation contribution to splices, connectors, couplers (events)
➤Length of fiber or distance to an event
➤Linearity of fiber loss per unit length (Attenuation discontinuities)
➤Reflectance or Optical Return Loss
Installation and Maintenance TestingDuring installation and maintenance we require different testing which is related to optical losses. During installation we test the length, attenuation, reflectance, end-to-end loss, optical return loss.
➤0.2 dB/km for single-mode fiber loss at 1550 nm;
➤0.35 dB/km for single-mode fiber loss at 1310 nm;
➤1 dB/km for multi-mode fiber loss at 1300 nm;
➤3 dB/km for multi-mode fiber loss at 850 nm;
➤0.05 dB for a fusion splice
➤0.1 dB for a mechanical splice;
➤0.2 - 0.5 dB for a connector pair;
➤3.5 dB for a 1 to 2 splitter (3 dB splitting loss plus 0.5 dB excess loss).
Type of losses occur in Connectors, patchcords and pigtails
|PC and APC contact surface|
Losses Occur in Optical Fiber
There are two types of absorption found in optical fiber-
1. Intrinsic absorption
2. Extrinsic absorption
1. Intrinsic absorption : The intrinsic absorption occur in the ultraviolet region, this absorption is not very common in practical but it happen due to the electronic absorption band. Basically in this absorption light particle interacts with an electron and stimulates it to a higher energy level.
The main reason for intrinsic absorption is that vibration frequency of atomic bonds in the infrared region. We all must have read in the basic concept of optical fiber that optical fiber is made of silica glass.Vibration of silicon-oxygen (Si-O) bonds create the absorption in the optical fiber.
The interplay between the vibrating bond and the electromagnetic field of the optical signal causes internal absorption. Due to the interaction between electromagnetic field and optical signal light energy is transferred from the electromagnetic field to the bond.
Radiation lossesThe loss of radiation is also called bending loss,bending in optical fiber more than bending radius, when the fiber is curved occur the radiation loss at that point. There are two types of radiation losses: micro-bending losses and macro bending.
Scattering lossBasically, scattering losses occur due to the interaction of light with density fluctuations within a fiber. Density changes when optical fiber is produced when optical fibers are manufactured.
Dispersion lossDispersion is a measure of temporal propagation that occurs when a light pulse propagates through an optical fiber. Dispersion is sometimes referred to as delay distortion in the sense that the delay of diffusion time makes the pulse wider.
You can also READ : Important Steps for FOC Splicing