Analysis of important indicators of optical power meter

In fiber optic systems, measuring optical power is the most basic, much like a multimeter in electronics. In fiber optic measurement, the optical power meter is a heavy duty common meter. By measuring the absolute power of the transmitter or optical network, an optical power meter can evaluate the performance of the optical equipment . Using an optical power meter in combination with a stable source, it is possible to measure connection loss, verify continuity, and help evaluate fiber link transmission quality.

What is an optical power meter? An optical power meter is used to measure absolute optical power or relative loss of optical power through a length of optical fiber.

When selecting an optical power meter, the most important technical indicator is the wavelength and range of the test. The unit of optical power is dbm. In the specification of the optical transceiver or switch, there is its illuminating and receiving optical power. Generally, the illuminating light is less than 0 dbm. The minimum optical power that the receiving end can receive is called sensitivity, and the maximum optical power that can be received is subtracted. The unit of sensitivity value is db (dbm-dbm=db), called dynamic range, and the illuminating power minus the receiving sensitivity is the allowable fiber attenuation value. The actual illuminating power at the time of testing minus the value of the actually received optical power. Is the fiber loss (db). The best value of the optical power received at the receiving end is the maximum optical power that can be received - (dynamic range / 2), but generally not so good. Due to the dynamics of each optical transceiver and optical module The range is different, so the specific amount of fiber can allow the attenuation depends on the actual situation. Generally, the allowable attenuation is about 15-30db.

Some optical power meter product specifications only have two parameters of luminous power and transmission distance. Sometimes, the transmission distance calculated by the attenuation per kilometer of fiber is mostly 0.5db/km. The minimum transmission distance is divided by 0.5. The maximum optical power that can be received. If the received optical power is higher than this value, the optical transceiver may be burned out. The maximum transmission distance divided by 0.5 is the sensitivity. If the received optical power is lower than this value, the link may be Will not work.

There are two ways to connect a fiber:

One is a fixed connection, one is an active connection, and the fixed connection is a fusion connection. The special connection is through discharge, and the optical fiber is melted to connect the two optical fibers together. The advantage is that the attenuation is small, and the disadvantage is that the operation is complicated and the flexibility is poor. Through the connector, usually the pigtail is connected to the ODF. The advantage is that * for simple flexibility, the disadvantage is that the attenuation is large.

Generally speaking, the attenuation of an active connection is equivalent to one kilometer of fiber. The attenuation of the fiber can be estimated by including fixed and active connections, and the attenuation of the fiber per kilometer is 0.5 db. If the active connection is relatively small, the value can be 0.4 db. Simple fiber does not include active connection, can be reduced to 0.3db, the theoretical value of pure fiber is 0.2db / km; for insurance, in most cases, 0.5 is better.