Wavelength scanning spectrum gas detection system and method based on double optical fiber annular cavities

Abstract

The invention discloses a wavelength scanning spectrum gas detection system and method based on double optical fiber annular cavities. A light source is divided into two paths of light signals through coupling devices and is divided into two loops; the first loop is a first light signal and is connected with the first coupling device and the second coupling device in sequence after passing through an isolator; the light signal is divided into two paths through the second coupling device; one path of the light signal passes through an optical fiber amplifier, an optical fiber filter and an optical fiber delay line in sequence and then is returned back to an input end of the first coupling device to form the optical fiber annular cavity; the other path of signal is transmitted to a photoelectric detection conversion circuit as an electric signal and the electric signal is amplified through a secondary amplification circuit; the second loop is symmetrical with the first loop; a gas chamber is additionally arranged between the optical fiber amplifier and the optical fiber filter; and the electric signal of the second loop enters the same self-balance detection circuit and is subjected to signal processing. A laser device driving signal type of a previous signal is changed and wavelength scanning pulse is introduced, so that a gas absorption peak can be directly observed; and the small drift amount of the wavelength of the light source can be identified through a positioning absorption peak device.

Description

technical field [0001] The invention relates to a wavelength scanning spectrum gas detection system and method based on a double optical fiber ring cavity. Background technique [0002] Since the industrial revolution in the 1760s, the demand for production capacity in coal, petroleum, chemical and other industries has continued to expand. While providing power for economic development, the toxic and harmful gases released by them have also brought huge hidden dangers to people's production and life. Therefore, the realization of safety monitoring of toxic and harmful gases has become one of the important problems to be solved in the field of environmental protection and industrial production, and the development of accurate, sensitive and fast gas sensors is one of the important prerequisites for solving this problem. . [0003] So far, all kinds of gas sensors have developed rapidly. Among them, the optical fiber gas sensor based on spectral absorption is favored by the m...

AI Technical Summary

Problems solved by technology

For the former, the researchers' proposals include self-balancing detection in Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology, harmonic detection in wavelength modulation spectrum photoacoustic spectroscopy, and spectral correlation detection. The essence is to suppress background noise. Improve the signal-to-noise ratio with the background baseline, increase the detection sensitivity and measurement accuracy, but factors such as light interference and detector sensitivity still limit the improvement space of its sensitivity and measurement accuracy; for the latter, researchers have successively proposed a plan to increase the gas absorption length , Cavity Ring-Down Spectroscopy (CRDS) technology and Fiber-loop Ring-down Spectroscopy (FLRDS) technology, although FLRDS technology overcomes the various shortcomings of the previous technology, it still faces its own unique shortcoming The board includes detection errors introduced by wavelength shift and gain saturation characteristics of erbium-doped fiber amplifiers

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