Optical attenuator is a very important fiber optic passive components. It’s an indispensable device for fiber CATV. So far the market has formed four series that are fixed-step, variable, continuously variable and intelligent optical attenuator.
Types of Optical Attenuators
A. Displacement Optical Attenuator
As we all know, when the two sections of optical fiber connection, must meet a really high accuracy, in order to make the optical signal a smaller loss transmission previously. Conversely, when the fiber to help make the appropriate alterations in the precision, you can control the amount of attenuation. Displacement-type optical attenuator is based on this principle, the intention of the fiber within the butt, the appearance of certain dislocation. The sunshine energy loss, in order to achieve the purpose of a controlled amount of attenuation, the displacement-type optical attenuator is divided into two types: the lateral displacement type optical attenuator, the axial displacement of the optical attenuator. The lateral displacement from the optical attenuator is a classical method, due to the magnitude from the lateral displacement parameters in the micron level, so generally do not have to produce a variable attenuator is used only for producing fixed attenuator, and the use of welding or stick connection, there is still a sizable market, the benefit of high return loss, generally more than 60 dB. Axial displacement type optical attenuator by mechanical means as long as the process design of two optical fibers a certain distance with the objective, is possible attenuation. This principle is mainly employed for producing fixed optical attenuator and some small variable optical attenuator.
B. Thin-film Optical Attenuator
This attenuator is created while using principle of sunshine in the reflected light concentration of the top of metal thin film film thickness. When the thickness from the metal thin film deposited around the glass substrate is bound, made of a set optical attenuator. Different attenuation can be obtained if inside a different thickness of a disk-shaped metallic thin wax glass substrate, metallic thin film, so that inserted within the optical road to different thicknesses so that you can alter the intensity of the reflected light within the optical fiber inserted obliquely deposited Cover made of the variable attenuator.
C. Attenuation-sheet Optical Attenuator
Attenuation the chip type optical attenuator directly fixed attenuator through an absorption characteristic in the end surface of the optical fiber or even the optical path to attain the reason for the attenuation from the optical signal, this process can not simply be used to produce a fixed optical attenuator can also be used to produce the variable optical attenuator.
Applications of Optical attenuators
A set optical attenuator fixed amount of attenuation of the optical road to the sunshine energy is principally used for its excellent temperature characteristics. Within the commissioning from the system, widely used in analog optical signal through the corresponding period of optical fiber attenuation or reduce the margin from the optical power the relay station may also be used to prevent saturation from the optical receiver; optical test instrument calibration scaling. For different line interface, you can use different fixed attenuator; if the interface is really a pigtail type available pigtail type optical attenuator welded towards the optical path between the two sections of fiber; If you are debugging the machine connector interface converter or inverter-type fixed attenuator.
In practical applications often require attenuation quantity of the optical attenuator could be changed using the user needs. Therefore, a wider range of applying the variable attenuator. For instance, EDFA, CATV optical system design margin of the particular product is not quite the same, the optical power margin of the system BER assessment, to prevent the receiver is saturated, it should be inserted within the system variable optical attenuator, another , fiber optics (such as a power meter or OTDR) measurement, calibration will also make use of the variable attenuator. From the perspective of market demand, on the one hand, the optical attenuator development toward miniaturization, serialization, low price direction. However, due to the common type optical attenuator, optical attenuator is development direction toward high-performance, intelligent optical attenuator, high return loss optical attenuator.
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