If the distance is to short and the attenuator is too close to the transmitter, the reflected light off the attenuator will be directed back towards the Tx laser. Which will also blow your transmitter. Also keeping attenuator at Rx will attenuate the noise along with the. 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. Figure 6-9 Fixed optical. An optical attenuator, or fiber optic attenuator, is a device used to reduce the power level of an optical signal, either in free space or in an optical fiber. The basic types of optical attenuators are fixed, step-wise variable, and continuously variable. It achieves this either by dispersing or absorbing the light without reflecting it.
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