① Attenuation and insertion loss.
Attenuation and insertion loss are important indexes of fiber optic attenuator. The attenuation index of fixed fiber optic attenuator is actually its insertion loss. In addition to attenuation, variable attenuator has separate insertion loss index. When the insertion loss of high-quality variable attenuator is less than 1.0db, the ordinary variable attenuator can be used when the index is less than 2.5dB. In the actual selection of adjustable attenuators, the smaller the insertion loss, the better. But it is bound to involve prices.
② Attenuation accuracy of fiber optic attenuator.
Attenuation accuracy is an important index of fiber optic attenuator. Generally, the attenuation precision of mechanical adjustable fiber optic attenuator is 0.1 times of its attenuation & plusmn. Its size depends on the precision machining degree of mechanical components. The attenuation accuracy of the fixed fiber optic attenuator is very high. Generally, the higher the attenuation accuracy, the higher the price.
③ Return loss.
The return loss is one of the most important parameters that affect the system performance. The influence of return light on optical network system is well known. The return loss of fiber optic attenuator refers to the ratio of the light energy incident into the fiber optic attenuator to the light energy reflected along the incident optical path in the attenuator. The return loss of high performance fiber optic attenuator is more than 45dB. In fact, due to process and other reasons, the actual return loss of the attenuator is still far from the theoretical value. In order not to reduce the return loss of the whole line, it is necessary to use a high return loss attenuator in the corresponding line, and at the same time, it is required that the fiber optic attenuator has a wider temperature range and spectrum range.
3. Application scope of fiber optic attenuator.
The fixed fiber optic attenuator is mainly used to attenuate the light energy in the optical path in a fixed amount, with excellent temperature characteristics. In the debugging of the system, it is often used to reduce the corresponding attenuation of the analog optical signal after passing through a section of optical fiber or to reduce the surplus optical power in the relay station, so as to prevent the saturation of the optical receiver; it can also be used for the calibration of the optical testing instrument. For different line interfaces, different Fixed Attenuators can be used; if the interface is pigtail type, pigtail type fiber optic attenuators can be welded between two sections of optical fiber in the optical path; if there is a connector interface in the process of system debugging, it is more convenient to use converter type or converter type fixed attenuators. In practical applications, fiber optic attenuators with variable attenuation are often needed. So variable attenuators are widely used. For example, because the design redundancy of EDFA and CATV optical system is not exactly the same as that of optical power in the actual system, variable fiber optic attenuators must be inserted into the system when BER evaluation is carried out to prevent receiver saturation. In addition, variable attenuators will also be used in the measurement and calibration of fiber optics (such as optical power meter or OTDR). From the perspective of market demand, on the one hand, fiber optic attenuators are developing towards miniaturization, serialization and low price. On the other hand, due to the maturity of ordinary fiber optic attenuators, fiber optic attenuators are developing in the direction of high performance, such as intelligent fiber optic attenuators, high return loss optical attenuators and so on.