Cavity ring-down spectroscopy-based tunable laser line width measurement method

A technology for cavity ring-down spectroscopy and laser tuning, which is applied in measurement devices, instruments, and optical devices, etc., can solve expensive and complex problems, and achieve the effects of high signal-to-noise ratio, convenient data processing, and high anti-interference ability.

Active Publication Date: 2011-01-19
INST OF OPTICS & ELECTRONICS - CHINESE ACAD OF SCI
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Problems solved by technology

Auto-differential interferometry can be used to resolve the laser linewidth of 1KHz, but this method requires a complex and expensive system, including a long section of single-mode fiber, an acousto-optic modulator, two fiber couplers and a spectrum analyzer Wait

Method used

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  • Cavity ring-down spectroscopy-based tunable laser line width measurement method
  • Cavity ring-down spectroscopy-based tunable laser line width measurement method
  • Cavity ring-down spectroscopy-based tunable laser line width measurement method

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Embodiment Construction

[0028] Attached below figure 1 The system describes the method for measuring linewidth of tunable lasers based on optical cavity ring-down spectroscopy of the present invention.

[0029] Light source 1 selects high beam quality (TEM 00 mode) tunable quantum cascade laser with a lasing wavelength of 1022.9cm -1 ~1028.4cm -1 , the spatial filtering and telescope system 2 consists of two lenses and a pinhole to shape the incident beam to match the optical cavity mode; two identical plano-concave high-reflection mirrors with high-reflection coating on the concave surface (reflectivity greater than 99% ) concave surface constitutes a ring-down cavity 3, the ring-down cavity is a stable cavity or a confocal cavity, and the cavity length L satisfies 0-24 cm-1 / mol cm -2 For a complete absorption line of magnitude, the chamber is filled with a dry mixture of carbon dioxide gas and nitrogen, wherein the carbon dioxide content accounts for about 4%, and the pressure in the chamber is...

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Abstract

The invention discloses a cavity ring-down spectroscopy-based tunable laser line width measurement method, and belongs to the technical field of photoelectric engineering. The method is characterized by comprising the following steps of: transmitting measured tunable laser beams into a stable resonant cavity consisting of two plane concave high reflectors, wherein gas with strong absorption spectral lines in a tunable laser output wave range is filled in the cavity; tuning the laser output wavelength to scan a complete gas absorption peak, wherein because the absorption strength of the gas is related with the incident light wavelengths and when the incident light wavelengths are different, the ring-down time of ring-down cavity output signals is different; and measuring the cavity ring-down time at each wavelength when the gas in the measurement cavity is absorbed, further obtaining gas absorption coefficients at different laser wavelengths, namely absorption spectrograms which are actual convolution of incident spectrums and gas absorption spectrums, and obtaining a spectrum curve line width and a gas absorption line width given in an HITRAN database by fitting so as to obtain the laser output spectrum line width. The invention provides a new method for laser line width measurement, the measurement result of the method is not affected by the laser strength fluctuation, and the method has the advantages of simple structure, high measurement precision and the like.

Description

technical field [0001] The invention relates to a method for measuring the output spectral line width of a laser, in particular to a method for measuring the output spectral line width of a wavelength tunable laser. Background technique [0002] With the development of laser technology, lasers have very important applications in many fields such as biomedicine, microprocessing, coherent detection, optical communication and high-precision spectroscopy, and in many cases, there are very strict requirements on the spectral linewidth characteristics of lasers. Requirements, such as in excimer laser lithography, fiber optic interference velocimetry, and trace gas detection systems, the linewidth characteristics of the laser play a decisive role in the performance of the entire system. Therefore, it is a very meaningful work to measure the laser linewidth. [0003] Traditional instruments for measuring the linewidth of lasers include spectrometers and Fabry-Perot interferometers....

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/02
Inventor 李斌成曲哲超刘卫静韩艳玲
Owner INST OF OPTICS & ELECTRONICS - CHINESE ACAD OF SCI
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