Hi there, Community friends!
This time, I will share with you the optical attenuator. Hope you like it!
An optical attenuator is a passive optical component containing light-absorbing materials. It is used to reduce the power level of an optical signal in an optical fiber in reverse to an optical amplifier.
The receiver of an optical module has an overload point. If the optical power received by the receiver is excessively high, the optical module will be burnt. Therefore, an optical attenuator is required to reduce the optical power. In addition, during signal transmission in a WDM system, the optical power of signals in each channel needs to be approximately the same to avoid transmission performance deterioration caused by uneven optical power. Therefore, an optical attenuator needs to be used to equalize the optical power in each channel.
Optical attenuators can be classified into fixed optical attenuators and variable optical attenuators based on whether the attenuation is variable.
1. FOA
A fixed optical attenuator (FOA) has a fixed attenuation level for the optical power in a fiber link, for example, 3 dB, 5 dB, or 10 dB. Theoretically, the attenuation level can be any value. Optical attenuators have multiple types of connectors, such as FC, SC, ST, and LC. They are simple in structure, easy to use, and low in cost. They are usually installed at the transmit end of active modules, such as OTU and OSC boards, to prevent the downstream receiver modules from being burnt due to excessively high output optical power. The disadvantage is that their usage lacks flexibility due to the fixed attenuation level.
2. MVOA
A variable optical attenuator (VOA) has a variable optical power attenuation in a fiber link. You can manually adjust the attenuation level to any value within the adjustment range. VOAs are classified into mechanical variable optical attenuators (MVOAs) and electrical variable optical attenuators (EVOAs) based on their adjustment modes.
A dedicated commissioning screw is used to rotate the knob and a meter is used to measure the attenuation level. When there are a large number of fibers, it is difficult to insert the commissioning screw into the knob of the MVOA. Besides, a test meter needs to be used to measure the attenuation level. Therefore, the use of an MVOA is complex. In addition, commissioning personnel must perform commissioning onsite, which requires high labor costs. Therefore, MVOAs are seldom used on live networks and are gradually replaced by EVOAs.
3. EVOA
The attenuation of an EVOA can be changed by applying a drive electrical signal. Therefore, the EVOA supports remote commissioning and commissioning personnel only need to issue commands on the NMS in the remote network management center to commission the attenuation of the EVOA. Therefore, EVOAs are mainly used on live networks. Generally, EVOAs are integrated into other boards instead of being used independently. For example, VA4, M48V, OAU1, and boards with WSS modules.
That's all, I welcome everyone to leave a message and exchange in the comment area!
