Atomic concentration and temperature detection device and method for alkali metal laser gain medium

Abstract

The invention belongs to the technical field of lasers, and discloses a tagged atom or tagged molecule based atomic concentration and temperature detection device and detection method for an alkali metal laser gain medium. According to the method, a tagged atom or tagged molecule in a ground state is added to the alkali metal laser gain medium, laser is shot to the gain medium by a probe, the laser frequency of the probe is tuned to the center frequency of an absorption spectrum of the tagged atom or tagged molecule, and the atomic concentration and medium temperature of alkali metal in a gain region under the pumping condition is obtained by measuring change of the laser transmission power of the probe after the laser is absorbed by the tagged atom or tagged molecule. The atomic concentration and temperature detection device and method for the alkali metal laser gain medium have the advantages that the structure is simple, the operation is simple and convenient, a measurement result is accurate, the anti-interference is high, timeliness is realized, the practicability is high, the technical difficulties in measurement of the atomic concentration and temperature in a pumping region of an alkali metal laser are solved, and an effective means is provided for performance evaluation and diagnostic test of the alkali metal laser.

Description

technical field [0001] The invention belongs to the technical field of lasers, and in particular relates to a detection device and a detection method for atomic concentration and temperature of an alkali metal laser gain medium based on tracer atoms or molecules. Background technique [0002] Diode pumped alkali vapor laser (DPAL) uses a semiconductor laser as a pump source to excite saturated vapor of alkali metal atoms (potassium, rubidium or cesium) to achieve laser output. This type of laser combines the advantages of semiconductor laser high power output and gas phase medium flow heat dissipation. It has high electro-optical conversion efficiency and high power output capability. It has potential application value in laser energy transmission, aerospace and military fields. The key factors for the stable operation of alkali metal lasers are to ensure the stability of the concentration of alkali metal atoms in the semiconductor pumping region and the low temperature rise...

AI Technical Summary

Problems solved by technology

[0003] At present, the commonly used methods for measuring the concentration of alkali metal atoms mainly include absorption spectroscopy and Faraday polarization rotation method: absorption spectroscopy is based on Beer’s law, and the concentration of alkali metal atoms is reversed by using the intensity change of a single-frequency probe laser passing through the vapor of alkali metal atoms. This method is suitable for the detection of alkali metal atoms in the ground state ( 2 S 1 / 2 state); however, in the high-intensity pumping region of DPAL, most of the alkali metal atoms are in a high-energy state (upper pump energy level 2 P 3 / 2 or laser upper level 2 P 1 / 2 ), what is measured by absorption spectroscopy at this time is the particle number difference between the energy levels corresponding to the probe laser frequency, not the total alkali metal atomic concentration, so it is not applicable; the Faraday polarization rotation method is based on the Faraday magneto-optical effect , determine the concentration of alkali metal atoms by measuring the rotation angle of the polarization state of the linearly polarized probe light after it passes through the alkali metal vapor. This method is suitable for measuring the high concentration of alkali metal atom vapor (>10 15 cm -3 ), the concentration of alkali metal atoms in DPAL is at 10 12 ~10 13 cm -3 The deflection angle obtained by this method is too small to achieve accurate measurement. At the same time, this method needs to apply a strong magnetic field, the structure is complicated, and the measurement process itself may affect the performance of DPAL, so it is not applicable

[0004] Based on the limitations of the above conventional measurement methods, people only use absorption spectroscopy to measure the concentration of alkali metal atoms and the temperature distribution gradient at the edge of the DPAL pumping region [C.Fox et al., Temperature gradients in diode-pumped alkali lasers, SPIE Newsroom, 2012 ], and based on this, the alkali metal atomic concentration and temperature rise in the pumping region were speculated [Que Yiqin et al., 100GHz spectral scanning measurement of the concentration of the gain medium of the alkali metal vapor laser, China Laser, 41(5), 2014], there is no Realize the measurement of the atomic concentration and temperature of the alkali metal gain medium in the semiconductor pump region

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