In a fiber optic communication system, an optical attenuator is an electronic device that is commonly used to decrease the level of power of an optical signal. In fiber optics, we refer to attenuation as a transmission loss. It is the decrease in light signal intensity as per the distance covered by the signal in a transmission medium. In large distances attenuation marks as an important element that limits the transmission of a digital signal traveling.
Optical fiber attenuators employ several principles when it is used in fiber-optic communications. Attenuators that utilize this principle are quite sensitive to the modal distribution ahead of the attenuator. So they need to be utilized at or near the transmitting end as you know.
There are three basic types of optical attenuators: the fixed attenuator, step-wise attenuator, and continuously variable attenuator. With negligible or no reflection fixed attenuators reduce light signals by a specific amount. This happens as signal reflection is not an issue and fixed attenuators are known for more accurate data transmission. Necessary elements that are associated with the optical isolator include the flatness over a specified frequency, amount of attenuation, range, voltage standing wave ratio (VSWR), average and peak power-handling capability, performance over a specific temperature, size, and height. In an electronic circuit, fixed attenuators are often used to enhance interstage matching. Many fixed attenuators are available from 5 dB to 25 dB. In rugged plug-in and connector models, the packaging of Mini-Circuits' fixed attenuators is done. In large distances, attenuation marks as an important element.
In variable optical attenuators (VOA), with solid-state devices such as the metal-semiconductor field-effect transistor (MESFETs) and PIN diodes, the resistors are replaced. The power ratio is adjusted by the optical circulator between the light beam coming from the device and the light beam entering the device at a changeable rate. Optical fiber attenuators employ several principles when it is used in fiber-optic communications. In fiber-optic communication systems, VOA is usually used to regulate optical power levels so that it can prevent damages in optical receivers which may be due to irregular or fluctuating power levels.
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