In the optical communication network, optical modules, optical fiber jumpers, active optical cables, etc. are all common and commonly heard products. However, Yifeiyang Communications is introducing another optical communication product, the optical attenuator. Do you know what this is?
What is an optical attenuator?
The optical attenuator is to attenuate the optical power by a predetermined amount in accordance with the user's requirements, in order to make the optical receiver not generate saturation distortion, or to satisfy certain tests in the optical line (such as system sensitivity test), or to balance The optical power of the transmission branch varies in size. Optical attenuators have adjustable optical attenuators and fixed optical attenuators. Optical attenuator specifications: Operating wavelength, return loss, attenuation and accuracy (attenuation range and resolution) and operating temperature are commonly used to evaluate system losses and various tests.
What is the principle of an optical attenuator?
Optical fiber attenuators usually absorb light to produce attenuation, such as sunglasses absorb additional light energy. Similarly, fiber attenuators have an operating wavelength range that can absorb light energy. At this wavelength, it should not reflect light because This may result in unwanted echo reflections in the fiber optic system. Another type of fiber attenuator utilizes a length of high loss fiber to reduce its input optical signal power and operates in such a manner that its output signal power is less than the input signal power. Optical power is reduced by absorption, reflection, diffusion, scattering, deflection, diffraction, and dispersion of the optical signal.
(1) Air isolation technology: The transmission of light in an optical fiber is restricted by the law of total reflection, and cannot be scattered out to maintain the relatively stable intensity. Once it is separated from the fiber, adding air gaps between the fiber and the fiber will cause the light to scatter and cause light attenuation.
(2) Displacement Dislocation Technology: This method is an effect that the core of two optical fibers is misaligned by a small amount of translation to achieve power loss.
(3) Attenuation fiber technology: Based on the absorption of light by metal ions, an attenuation fiber with mixed metal ions is developed. The attenuated fiber is penetrated into the ceramic ferrule. After a special process, a fixed attenuator of yin and yang can be made.
(4) Absorption glass method: The optically polished neutral absorption glass sheet can also be applied to the production of an optical attenuator.
The main application of fiber attenuator
Optical fiber communication network, optical data network, optical fiber CATV network, high-power optical device measurement, line evaluation, connection between devices, adjustment and so on.
When is the optical attenuator used?
With the development of the optical communication industry and the improvement of process manufacturing, the loss of optical fiber devices, such as optical cables and connectors, is continuously decreasing and is less than the designed attenuation. This may cause the optical receiver to receive more optical power than it has. Withstand range, saturation distortion. Therefore, in order to reduce the signal received by the optical receiver, an optical attenuator is needed to control the optical power within a certain range.
See the figure below:
The optical attenuator controls the optical power range in optical fiber communication, avoiding saturation distortion of the optical power;
So, what are the advantages and disadvantages of optical attenuators?
1, air isolation technology is low, simple to implement, small size, low cost. Fixed and continuously adjustable. However, due to the abrupt change of the conducting optical medium, the refractive index of the interface between the core and the air is different, input light will be emitted within this interface, and part of the light will be reflected back along the input path, resulting in a small return loss of the transmission line. For high demand lines, it is difficult to meet.
2. The displacement misalignment technology adopts ordinary optical fiber, which has low cost and realizes fixed attenuation. The replaceable connector can be used in the circuit. Its misalignment of the fiber also reduces return loss.
3. The attenuating fiber is specially designed to provide flat attenuation in the widest possible wavelength range. The consistent attenuation of UWB ensures that the product is fully compatible with DWDM, CATV and other communication systems now and in the future. Attenuating fiber geometry is consistent with common single-mode fiber, ensuring perfect fit with the ceramic ferrule, thus achieving such an attenuator as the connector, has a very high return loss, and has the advantage of small size. But only as a fixed attenuator.
4, light absorption glass can be fixed and adjustable. However, the development of the attenuator requires the use of an optical collimator, which requires a high degree of coupling between the input and output terminals, and requires a high-precision debugging device and supporting components. Higher implementation costs.
5. Attenuators using solid-state light attenuation technology can be continuously adjustable. However, the technical aspects of these new technologies involve a wide range of costs and are relatively costly. They also have the disadvantages of temperature, reliability, and packaging. For these technologies need further improvement.
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