Fiber optic attenuator is used in the fiber optic communications to reduce the optical fiber power at a certain level, the most commonly used type is female to male plug type fiber optic attenuator, it has the optical fiber connector at one side and the other side is a female type fiber optic adapter, fiber optic attenuator name is based on the connector type and the attenuation level.
There are two functional types of fiber attenuators: plug style (including bulkhead) and in-line.
A plug style attenuator is employed as a male-female connector where attenuation occurs inside the device, that is, on the light path from one ferrule to another. These include FC fiber optic attenuator, LC attenuator, SC attenuator, ST attenuator and more.
An in-line attenuator is connected to a transmission fiber by splicing its two pigtails.
The principle of operation of attenuators are markedly different because they use various phenomena to decrease the power of the propagating light. The simplest means is to bend a fiber. Coil a patch cable several times around a pencil while measuring the attenuation with a power meter, then tape this coil. Then you got a primitive but working attenuator.
Most attenuators have fixed values that are specified in decibels (dB). They are called fiber optic fixed attenuator. For example, a -3dB attenuator should reduce intensity of the output by 3dB.
Manufacturers use various types of light-absorbing material to achieve well-controlled and stable attenuation. For example, a fiber doped with a transition metal that absorbs light in a predictable way and disperses absorbed energy as a heat.
Variable fiber optic attenuators also are available, but they usually are precision instruments used in making measurements.
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