Wavelength locking device for laser in off-axis integral cavity system and locking method thereof

Abstract

The invention discloses a wavelength locking device for a laser in an off-axis integral cavity system and a locking method thereof. The device comprises a temperature current controller (11), a laser(1), an optical fiber (2), to-be-detected gas and a photoelectric sensor (6). Particularly, the to-be-detected gas is positioned in an off-axis optical resonant cavity (4); and a wavelength locking part (12) comprises a data acquisition analysis device (7), a simulation PID device (8), an adder (10) and a sawtooth wave generator (9). The method comprises the steps of: modulating the laser by adopting a sawtooth wave and carrying out interception on an acquired signal according to data segments which contain a complete to-be-detected gas absorption peak and are equal in length; and carrying outlinear correlation operation on a first data segment intercepted and a data segment intercepted when one data point is added subsequently, so as to acquire a drifting signal of a central wavelength of the laser. An output frequency of the laser can be stabilized on a specific absorption peak, and the wavelength locking device and the locking method can be widely used for trace gas concentration detection and substance chemical component analysis on the basis of the off-axis integral cavity system.

Description

technical field [0001] The invention relates to a wavelength locking device and a locking method of a laser, in particular to a wavelength locking device and a locking method of a laser used in an off-axis integrating cavity system. Background technique [0002] Detecting trace gas concentrations has a wide range of applications in the fields of environmental monitoring, atmospheric chemistry, diagnostic medicine, and molecular astrophysics. In recent years, with the rapid development of laser technology, absorption spectroscopy technology has also developed rapidly; off-axis integral cavity absorption spectroscopy technology, as a high-sensitivity and high-stability detection technology in absorption spectroscopy technology, can achieve low concentration High-precision detection and application in the environment. In practical applications, the off-axis integrating cavity system based on the off-axis integrating cavity absorption spectroscopy technology usually chooses a t...

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Problems solved by technology

Although this locking device and locking method can stabilize the operating frequency of the semiconductor laser on a specific absorption peak, there are shortcomings for the off-axis integrating cavity system where the gas to be measured is placed in the optical cavity. First of all, due to the large cavity mode noise of the off-axis integrating cavity, it is difficult to determine the real distance between the two absorption peaks, resulting in a large error in the feedback signal, which makes it impossible to lock the wavelength; secondly, considering the actual acquisition and calculation For practical problems such as processing speed, the sawtooth wave is usually used as the scanning signal, and thus produces two asymmetrical absorption peaks, which will also cause large errors, resulting in the inability to lock the wavelength

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