Method for generating ultra wide band mid-infrared laser in single polarized crystal

Abstract

The invention relates to the technical field of strong laser nonlinear frequency conversion, in particular to a method for generating ultra-wideband intermediate infrared laser in a single polarized crystal, which comprises the following steps of: generating a difference frequency conversion process in the polarized crystal by using laser with the wavelength of 800nm as pump light and laser with the wavelength of 0.95-1.6 mu m as signal light, thereby generating intermediate infrared laser with the wavelength of 1.6-5 mu m. In the method, a polarization crystal with a chirp period structure is used, namely, the polarization period of the crystal continuously changes along with the change of the position in the crystal. And the polarized crystal is a chirp periodically poled lithium niobate crystal doped with 5% of magnesium oxide. By utilizing a quasi-phase matching technology, the maximum effective nonlinear coefficient of the chirp period lithium niobate crystal can be used, so that the crystal angle or the polarization of laser does not need to be changed when the chirp period lithium niobate crystal is pumped at different wavelengths; the defect that the wavelength is difficult to expand due to the fact that an existing mid-infrared band laser is limited by a gain medium is overcome.

Description

technical field [0001] The invention relates to the technical field of strong laser nonlinear frequency conversion, in particular to a method for generating an ultra-wideband mid-infrared laser in a monolithic polarized crystal. Background technique [0002] Due to the particularity of photon energy, the 3-5 μm mid-infrared laser has a wide range of application values ​​in basic research, biomedicine, optical communication, atmospheric detection, etc. However, limited by the gain medium in the mid-infrared band, traditional laser generation and amplification methods such as regenerative amplification are no longer applicable. Second-order nonlinear frequency conversion, such as second harmonic generation (SHG), sum frequency generation (SFG), difference frequency generation (DFG), optical parametric oscillation (OPO), and amplification (OPA) processes, has been widely used in lasers frequency extension. Through the difference frequency conversion, the near-infrared laser w...

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Problems solved by technology

[0003] In order to solve the above problems, the present invention provides a method that can realize the generation of mid-infrared laser in the 1.6-5 μm band at the same time, and has the advantages of convenient use, controllable structure, and flexible design; it overcomes the difficulty of traditional infrared laser tuning, occupies a large area, and Ultra-broadband mid-infrared laser generation method in monolithic polarized crystals with shortcomings such as inability to extend to mid-infrared

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