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Basic Knowledge About Fiber Optic Attenuator

Basic Knowledge About Fiber Optic Attenuator

Fiber optic attenuator is a device that is inserted into a fiber optic system to reduce the power of the signal. Fiber attenuators can be used to protect the fiber from damage, to adjust the power level margins of the signal, or to improve the signal-to-noise ratio. Optic attenuators come in a variety of types, including fixed, variable, and step-attenuators.

1. What are fiber attenuators and what do they do?

Fiber attenuators are devices that are used to reduce the power of optical signal that is being transmitted through a fiber optic cable. They are typically used to protect the fiber optic cable from being damaged by too much power, or to adjust the signal strength to match the requirements of the receiving device, it can be used separately or installed in the optic fiber box or patch panel.

 

What are fiber attenuators

What are fiber attenuators

2. What types of fiber optic attenuator?

There are a variety of different types of fiber attenuators, each with its own set of benefits and drawbacks. Some of the most common types of fiber attenuators include inline attenuators, patch cord attenuators, bulkhead attenuators, or variable attenuators.
Female to Female inline type attenuator is the simplest type of fiber attenuator. They are typically installed in between the transmitter and the fiber optic cable, and they reduce the power of the signal by a fixed amount, the attenuation element inside is a neutral density filter.
Patch cord attenuator is similar to inline attenuator, but they can be adjusted to provide a variable amount of attenuation. This makes them ideal for situations where the signal strength needs to be adjusted on the fly, the patch cable can be in single mode or multi-mode.
Bulkhead fixed optical attenuators are installed in between the transmitter and the receiver, and they are typically used to connect two fiber optic cables together. They provide a fixed amount of attenuation, and they are often used to prevent the power of the signal from being too strong.
Compared to fixed attenuator, variable attenuators refer to an attenuator that can adjust the level of attenuation arbitrarily. This attenuator has a more complex structure and price depends on the attenuation range.

types of fiber optic attenuator

types of fiber optic attenuator

3. What to Consider When Choosing a Fiber Attenuator

When you are looking for a fiber attenuator, there are a few things you should consider. The first is the connector type. The attenuator should have the same connector type as the fiber you are using. The next thing to consider is the attenuation value. The attenuator should have an attenuation value that is appropriate for your application. The third thing is the return loss of the attenuator. The last thing to consider is the operating wavelength. The attenuator should have a wavelength range that is compatible with the fiber you are using.

consider dimension when choosing optic attenuator

consider dimension when choosing optic attenuator

4. Fiber Attenuator Performance

4.1 Attenuation and insertion loss

The attenuation index of the fixed optical attenuator is its insertion loss. In addition to the attenuation, the variable optical attenuator also has a separate insertion loss index requirement. Insertion loss is from the insertion loss of the fiber collimator and the transmittance accuracy of the attenuation unit, among which the coupling process focuses on the production of the fiber collimator, including the coupling between the fiber and the self-focusing lens, and the coupling between a pair of fiber collimating mirrors.

optic attenuator loss reason

optic attenuator loss reason

4.2 Attenuation Accuracy of Optical Attenuators

Usually, the attenuation accuracy of a mechanical optical attenuator is 0.1dB of its attenuation. The attenuation of the attenuator type attenuator depends on the transmittance and uniformity of the metal chip coating layer.
The optical attenuator of mechanical structure, reading display mode and mechanical adjustment method affect the attenuation accuracy of the optical attenuator.

4.3 Return Loss

The ratio of the optical power incident into the optical attenuator to the fiber optic power reflected from the attenuator along the incident optical path. The return loss of the high-performance optical attenuator is above 40dB, and the source of the return loss is the reflection caused by the mismatch of the refractive index of each component and the air. Methods to improve return loss include anti-reflection coating, use of inclined lenses, tilting of each optical element, mechanical index matching, etc.

5. Applications of Optical Attenuators

It is mainly used to attenuate the optical power in the optical path. Among the passive devices, its products are only fixed with connectors and couplers. The optical attenuator has the advantages of low price, stable performance and convenient use, and the market demand is large, while the variable optical attenuator is flexible, and the market demand is growing steadily.

 

6. Summarize

Fiber optic attenuators play a key role in protecting fiber optic transmission equipment. If the optical power is not properly reduced, it will cause damage to the equipment or signal distortion. Downtime is an obvious possibility if too much damage is done. In a fiber optical communication system, every device counts, no matter how simple or small it is. It is these tiny devices, like fiber optic attenuators, fiber cables and adapters , that make the whole system possible and operate without problems.

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