Optical power meter operation and precautions

Used to measure the absolute optical power or the relative loss of optical power through a section of optical fiber. In optical fiber systems, measuring optical power is the most basic, very much like a multimeter in electronics. In optical fiber measurements, optical power meters are the most common meters for heavy duty. By measuring the absolute power of a transmitter or optical network, an optical power meter can evaluate the performance of optical terminal equipment. Used in combination with a stable light source, an optical power meter can measure connection loss, verify continuity, and help evaluate the transmission quality of a fiber optic link.

How to operate

To select a suitable optical power meter for your specific application, you should pay attention to the following points:

1. Choose the best probe type and interface type

2. Evaluate the calibration accuracy and manufacturing calibration procedures to match the range of your fiber and connector requirements.

3. Make sure these models are consistent with your measurement range and display resolution.

4. It has the dB function of direct insertion loss measurement.

Precautions

The unit of optical power is dBm. The manual of the optical transceiver or switch contains its emitting and receiving optical power. Usually, the emitting light is less than 0 dBm. The minimum optical power that the receiving end can receive is called sensitivity. The unit of the value of the maximum optical power that can be received minus the sensitivity is db (dbm-dbm=db), which is called dynamic range. The emitting power minus the receiving sensitivity is the allowable optical fiber attenuation value. During the test, the actual emitting power minus the actual received optical power is the optical fiber attenuation (db). The optimal value of the optical power received by the receiving end is the maximum optical power that can be received - (dynamic range/2), but it is generally not so good. Since the dynamic range of each optical transceiver and optical module is different, the specific allowable attenuation of the optical fiber depends on the actual situation. Generally speaking, the allowable attenuation is about 15-30db.

Some manuals only have two parameters: luminous power and transmission distance. Sometimes, the transmission distance is calculated based on the fiber attenuation per kilometer, which is usually 0.5db/km. Divide the minimum transmission distance by 0.5 to get 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. Divide the maximum transmission distance by 0.5 to get the sensitivity. If the received optical power is lower than this value, the link may not work.

There are two ways to connect optical fiber, one is fixed connection and the other is active connection. Fixed connection is fusion splicing, which uses special equipment to melt the optical fiber through discharge to connect two sections of optical fiber together. The advantage is low attenuation, but the disadvantage is complicated operation and poor flexibility. Active connection is through connectors, usually connected to pigtails on ODF. The advantage is simple operation and good flexibility, but the disadvantage is high 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 as follows: including fixed and active connections, the attenuation of optical fiber per kilometer is 0.5db. If there are very few active connections, this value can be 0.4db. For pure optical fiber without active connections, it can be reduced to 0.3db. The theoretical value of pure optical fiber is 0.2db/km; for insurance purposes, 0.5 is better in most cases.

The fiber test TX and RX must be tested separately. In the case of single fiber, since only one fiber is used, only one test is required. The implementation principle of single fiber is wavelength division multiplexing according to the manufacturer, but I think it is more likely to use a fiber coupler.

What is an optical power meter? It is used to measure the absolute optical power or the relative loss of optical power through a section of optical fiber. In optical fiber systems, it is very similar to a multimeter in electronics. In optical fiber measurements, optical power meters are heavy-duty common meters. By measuring the absolute power of a transmitter or optical network, an optical power meter can evaluate the performance of optical terminal equipment. When used in combination with a stable light source, an optical power meter can measure connection loss, verify continuity, and help evaluate the transmission quality of optical fiber links.

To select a suitable optical power meter for your specific application, you should pay attention to the following points:

1. Choose the best probe type and interface type

2. Evaluate the calibration accuracy and manufacturing calibration procedures to match the range of your fiber and connector requirements.

3. Make sure these models are consistent with your measurement range and display resolution.

4. It has the dB function of direct insertion loss measurement.

The unit of optical power is dBm. The manual of the optical transceiver or switch contains its emitting and receiving optical power. Usually, the emitting light is less than 0 dBm. The minimum optical power that the receiving end can receive is called sensitivity. The unit of the value of the maximum optical power that can be received minus the sensitivity is db (dbm-dbm=db), which is called dynamic range. The emitting power minus the receiving sensitivity is the allowable optical fiber attenuation value. During the test, the actual emitting power minus the actual received optical power is the optical fiber attenuation (db). The optimal value of the optical power received by the receiving end is the maximum optical power that can be received - (dynamic range/2), but it is generally not so good. Since the dynamic range of each optical transceiver and optical module is different, the specific allowable attenuation of the optical fiber depends on the actual situation. Generally speaking, the allowable attenuation is about 15-30db.

Some manuals only have two parameters: luminous power and transmission distance. Sometimes, the transmission distance is calculated based on the fiber attenuation per kilometer, which is usually 0.5db/km. Divide the minimum transmission distance by 0.5 to get 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. Divide the maximum transmission distance by 0.5 to get the sensitivity. If the received optical power is lower than this value, the link may not work.

There are two ways to connect optical fiber, one is fixed connection and the other is active connection. Fixed connection is fusion splicing, which uses special equipment to melt the optical fiber through discharge to connect two sections of optical fiber together. The advantage is low attenuation, but the disadvantage is that the operation is complex and the flexibility is poor. Active connection is through connectors, usually connected to pigtails on ODF, the advantage is simple operation and good flexibility, the disadvantage is high 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 as follows: including fixed and active connections, the attenuation of optical fiber per kilometer is 0.5db. If the active connection is quite small, this value can be 0.4db. If the optical fiber does not include active connections, it can be reduced to 0.3db. The theoretical value of pure optical fiber is 0.2db/km; for insurance purposes, 0.5 is better in most cases.

The fiber test TX and RX must be tested separately. In the case of single fiber, since only one fiber is used, only one test is required. The implementation principle of single fiber is wavelength division multiplexing according to the manufacturer, but I think it is more likely to use a fiber coupler.