How To Test The Performance Of Optical Fiber

- May 21, 2020-

How To Test The Performance Of Optical Fiber


Optical fiber is the foundation of our network transmission, so we should understand it in detail. Similarly, it has many characteristics. For example, the basic requirements of optical fiber include continuity, so it is one of the basic concepts of optical fiber testing. There is also a lot of related equipment, such as fiber attenuator, fiber optic cable, fiber panel, fiber splitter, etc., so the fiber is a huge and potential, let us learn how the performance of fiber test.


How To Test The Performance Of Optical Fiber

When performing continuity measurements, a red laser, light emitting diode (LED), or other visible light is usually injected into the fiber, and the light output is monitored at the end of the fiber. If there are breaks or other discontinuities in the fiber, the optical power at the output end of the fiber will be reduced or there will be no light output at all.


After the light is transmitted through the optical fiber, the attenuation of power can also indicate the conductive performance of the optical fiber. If the attenuation of the fiber is too large, the system will not work properly. Optical power meters and light sources are general equipment for measuring the transmission characteristics of optical fibers.


An optical power meter is a photodiode that converts input light into a measurable signal. Silicon photodiodes are more sensitive in the range of 4OO to 1000nm, and are suitable for the measurement of fiber transmission characteristics at 650 and 850nm. Germanium (Ge) and indium are arsenized one by one. Potassium (In GaAs) photodiodes can cover 800 to 1600 nm, so they are most suitable as photodetectors in 1300 nm or 1500 nm fiber optic systems. The detector of germanium material is cheaper than the detector of indium-potassium arsenide type, but the noise is larger. If the signal level to be measured is very low, you must use an indium-potassium arsenide or a cooled small area germanium detector. Conversely, if the signal is strong, it should be attenuated to avoid saturating the photodiode and producing erroneous results.


Fiber attenuation is also one of the parameters we often measure. The attenuation of the optical fiber is mainly caused by the inherent absorption and scattering of the optical fiber itself, which is usually expressed by the attenuation coefficient α of the optical fiber, and the unit is dB / km.


The attenuation coefficient of single-mode fiber is generally 0.5dB / km at 1550nm, while the graded-index glass fiber is 1dB / km at 1300nm and 3dB / km at 850nm. The attenuation of plastic optical fiber is greater, about 200dB / km at 650nm. Although plastic optical fiber has recently received attention, experts believe that due to the limitation of the principle loss of plastic optical fiber, its practical length can only be a few hundred meters at most.


The attenuation coefficient should be measured at many wavelengths, so it is best to use a monochromator as the light source, LED can also be used as the test source for multimode fiber, and laser as the test source for single mode fiber. Because the laser will produce a speckle pattern in the receiver, causing measurement uncertainty.


When selecting a test light source, it is necessary to adapt its spectrum and fiber coupling characteristics to the characteristics of the light source used in the fiber system itself. The performance of optical fiber is mainly based on the quality and variety of optical fiber products. There are many types of optical fiber products. For example, optical fiber adapters are divided into st adapters, sc adapters, fc adapters, and lc adapters.


OPTICO optical communication experts suggest that fiber optics still need greater improvement at present, because many fiber channels or modes will cause the light in the fiber to diverge. So we must choose standard products when purchasing optical fiber products. There are many OPTICO fiber products such as optical fiber jumpers, PLC splitters, optical FTTH set, DWDM, SFP, etc. All the products adopt strict quality standards in the production and inspection, ensuring excellent operation performance and good product stability, and safely and reliably ensuring the long-term use of products.

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