Method for regulating best matching state of type-II KDP (Potassium Dihydrogen Phosphate) crystal for frequency multiplication of infrared light

Abstract

The invention discloses a method for regulating best matching state of a type-II KDP crystal for frequency multiplication of infrared light. Adopted devices comprise a He-Ne light source, a pore aperture, a long-focus lens, a Rochon prism, a photoelectric probe and an oscilloscope. The method comprises the following steps of: firstly, roughly regulating a phase matching angle of the KDP crystal by using an auxiliary light source; secondly, focusing generated weak green lights on the Rochon prism via the long-focus lens, and regulating an azimuth angle of the KDP crystal according to the characteristics of the emergent light of the Rochon prism; and finally, regulating the phase matching angle of the KDP crystal by means of the photoelectric probe and the oscilloscope till the second frequency-multiplied output is the maximum. The method for regulating best matching state of the type-II KDP crystal for frequency multiplication of infrared light disclosed by the invention is characterized in that the azimuth angle of the KDP crystal is regulated by smartly utilizing the polarization detection characteristics of the Rochon prism and the KDP crystal is conveniently regulated in the weaker fundamental frequency light; the frequency multiplication efficiency of the KDP crystal is optimized and the polarization state of the frequency multiplication is guaranteed. The method for regulating best matching state of the type-II KDP crystal for frequency multiplication of infrared light disclosed by the invention has the characteristics of convenience in regulation, simpleness and high efficiency, and strong practicability.

Description

technical field [0001] The invention relates to a high-energy frequency-doubling laser system, in particular to a method for adjusting the optimal matching state of a class II KDP crystal to frequency-doubling infrared light. Background technique [0002] Ultra-short and ultra-intense lasers will provide new research means for the development of strong-field ultra-fast science, relativistic nonlinear physics, and astrophysics. This technology has developed rapidly since the mid-1980s, including in my country. The world's major scientific and technological powers have successively established large-scale high-power ultrashort pulse laser devices. In femtosecond-level ultrafast laser systems, chirped pulse amplification (CPA) based on Ti:Sapphire crystals is the main technical route; while large-aperture KDP crystals are the main frequency-doubling crystals for 1053nm fundamental frequency light, Therefore, improving the output efficiency of the KDP crystal as much as possible...

AI Technical Summary

Problems solved by technology

[0005] At present, in the high-energy PW laser system, the main steps of the adjustment method of the large-aperture KDP frequency-doubling crystal can be summarized as follows: the KDP frequency-doubling crystal is placed behind the amplifier, and the light is incident on the center of the crystal; the phase matching angle of the KDP crystal is adjusted and Azimuth, at the same time use white paper to observe the intensity of the green light behind the KDP, stop rotating until the green light is the strongest, and fix the KDP crystal frame; this method mainly has the following disadvantages: because the fundamental frequency light is invisible light, and the general KDP crystal The surface is coated with 1053nm anti-reflection coating. It is very difficult to directly observe whether the fundamental frequency light is vertically incident on the crystal surface; using human eyes to observe the intensity of green light can easily cause eye fatigue, resulting in inaccurate judgment and affecting the multiplier output. ; Even when the output green light is the strongest, the polarization state of the corresponding output light may not necessarily be horizontally polarized light, but may also be vertically polarized light; this method requires multiple single-shot experiments to obtain higher frequency doubling efficiency , it takes a long time, and the frequency doubling efficiency cannot be maximized, and the polarization state of the output light cannot be guaranteed

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