Fixed Value vs. Variable fiber Optic Attenuators: Which One to Choose for Your Fiber Optic Network?

Fiber optic attenuators, also known as optical attenuators, play a crucial role in maintaining the performance of fiber optic receivers. These devices function by reducing the light power that reaches the receiver, thereby preventing overload and degradation of the bit error ratio. In simple terms, too much light can cause problems for fiber optic receivers, and attenuators are used to reduce the power of the light to achieve the best bit error ratio.
 
Fiber Attenuators work in a manner similar to sunglasses, absorbing the extra light energy to protect the receiver. A key feature of a good fiber attenuator is that it should absorb the extra light without reflecting it or getting damaged. Fiber optic attenuators come in two types: fixed value attenuators and variable optical attenuators.
 
Fixed value attenuators have a specified value in decibels and are widely used in telecommunication networks, optical fiber test facilities, LAN, and CATV systems. They can be either in-line type or connector type. In-line type looks like an ordinary fiber patch cable, while connector type attenuator resembles a bulkhead fiber connector with a male and female end that mates to regular connectors of the same type.
 
Variable optical attenuators, on the other hand, have a variety of designs and are commonly used for testing and measurement. They also have a wide usage in EDFAs for equalizing the light power among different channels. One type of variable optical attenuator is made on the D-shaped fiber as a type of evanescent field device. By replacing a part of the evanescent field reachable cladding with a bulk external material, whose refractive index is larger than the mode effective index, the mode can become leaky and some of the optical power can be radiated. If the index of the external material can be changed with a controllable mean, a device with controllable attenuation is achievable.
 
In conclusion, fiber optic attenuators play a crucial role in maintaining the performance of fiber optic receivers by reducing the light power that reaches the receiver. Fixed value and variable optical attenuators are the two main types of attenuators used in fiber optic communications. A good fiber attenuator should absorb the extra light without reflecting it or getting damaged.