Views:1 Author:Ada Ru Publish Time: 2021-10-28 Origin:Site
The unit of optical power is dbm. It has its luminous and received optical power in the manual of the fiber optic transceiver or switch. Usually the luminous is less than 0dbm. The minimum optical power that the receiving end can receive is called sensitivity, and the large optical power that can be received is subtracted The unit of the sensitivity value is db (dbm-dbm=db), which is called the dynamic range. The luminous power minus the receiving sensitivity is the allowable fiber attenuation value.
The value of the actual luminous power minus the actual received optical power during the optical power meter test is the fiber attenuation (db), and the best value of the optical power received by the receiving end is the large optical power that can be received-(dynamic range/2 ), but generally not so good. Because the dynamic range of each optical transceiver and optical module is different, the specific allowable attenuation of the fiber depends on the actual situation. Generally, the allowable attenuation is about 15-30db.
Some manuals will only have two parameters: the luminous power of the optical power meter and the transmission distance. Sometimes it will explain the transmission distance calculated by the fiber attenuation per kilometer, mostly 0.5db/km; divide the minimum transmission distance by 0.5, which is The maximum optical power that can be received. If the received optical power is higher than this value, the optical transceiver may be burned; divide the maximum transmission distance by 0.5, which is the sensitivity. If the received optical power is lower than this value, the link The road may be blocked.
There are two ways to connect optical fibers. One is fixed connection and the other is movable connection. Fixed connection is fusion splicing. It uses special equipment to melt the optical fiber to connect the two optical fibers together. The advantage is that the attenuation is small, but the disadvantage is The operation is complicated and flexible.
The active connection is through the connector, usually the pigtail is connected to the ODF. The advantage is simple operation and flexibility. The disadvantage is large attenuation. Generally speaking, the attenuation of an active connection is equivalent to one kilometer of optical fiber. The attenuation of optical fiber can be estimated like this : Including fixed and movable connections, the optical fiber attenuation per kilometer is 0.5db. If the active connection is quite small, this value can be 0.4db. Pure optical fiber does not include the active connection, which can be reduced to 0.3db. The theoretical value of pure optical fiber is 0.2db/km ; In most cases, 0.5 is better for insurance.
Optical power meter fiber test TX and RX must be tested separately. In the case of single fiber, because only one fiber is used, of course it only needs to be tested once. According to the production company, the realization principle of single fiber is wavelength division multiplexing, but it is generally believed that fiber coupling is used. The possibility of the device is higher.