Method for measuring optical fiber dispersion based on optical switch laser beat-frequency system

Abstract

The invention discloses a method for measuring optical fiber dispersion based on an optical switch laser beat-frequency system, which is characterized in that optical fiber gratings with different central wavelengths are selected through adjusting an optical switch, variations in beat frequency in a laser resonant cavity are realized, variations in laser beat frequency before and after an optical fiber to be measured is added to an optical path are measured respectively by using a spectrum analyzer, and a relation between the variation in laser beat frequency before and after the optical fiber to be measured is added to the optical path and the corresponding dispersion of the optical fiber to be measured is established, so that measurement for the dispersion of the optical fiber to be measured under different wavelengths is enabled to be converted into measurement for the variation in laser beat frequency, and measurement for the dispersion of the optical fiber to be measured is realized through data processing. According to the invention, the optical fiber dispersion is measured by using multi-longitudinal mode beat-frequency signals, so that the method is not affected by the system loss and light source fluctuations, and measurement for the dispersion of the optical fiber to be measured is successfully realized. The method is not only good in stability, simple in structure of a measurement system and low in cost, but also converts optical signal measurement into electric signal measurement, thereby being convenient to perform data processing.

Description

technical field [0001] The invention belongs to the technical field of optical fiber dispersion measurement, and in particular relates to a method for measuring optical fiber dispersion based on an optical switch laser beat frequency system. Background technique [0002] The dispersion problem of the optical fiber communication system has always been a hot spot that people pay attention to. With the continuous improvement of the system transmission rate, the intersymbol interference caused by various types of dispersion has become one of the main limiting factors of the capacity of the optical communication system. Technical means to compensate for dispersion. But for the DWDM system, a certain amount of dispersion is needed to reduce the four-wave mixing caused by nonlinear effects. Therefore, before the system is put into use, various dispersions should be measured to determine the required dispersion management scheme. [0003] The essence of optical fiber dispersion me...

AI Technical Summary

Problems solved by technology

There are many methods for measuring optical fiber dispersion, mainly three kinds, instant delay method, interference method and phase shift method, among which the measurement accuracy of time delay method is mainly limited by the width of optical pulse, the bandwidth of photodetector and the stability of laser light source and electronic devices The phase-shift method is widely used, and commercial dispersion measurement instruments basically use the phase-shift method, but the phase-shift method usually requires a very stable tunable laser, and even needs to be combined with a vector network analyzer to achieve frequency sweep, resulting in measurement costs Greatly increased; interferometric measurement is a method that people have studied most in recent years. It has high measurement accuracy, relatively simple structure, and can measure short optical fibers. It is suitable for dispersion measurement of expensive special optical fibers, such as photonic crystal optical fibers.

The above methods generally have the defects of complex structure, inconvenient operation and high measurement cost. Therefore, it is necessary to design a method for measuring optical fiber dispersion based on an optical switch laser beat frequency system.

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