Four-wave mixing scanning type ultrashort laser pulse time domain contrast measuring instrument

Abstract

The invention relates to a four-wave mixing scanning type ultrashort laser pulse time domain contrast measuring instrument, which comprises a beam splitter, a short-pass filter, a first planar reflecting mirror, a second planar reflecting mirror, a third planar reflecting mirror, a fourth planar reflecting mirror, an electric translation platform, a fifth plane reflecting mirror, a first cylindrical reflecting mirror, a second cylindrical reflecting mirror, a third-order nonlinear crystal, an attenuator, a filter, a detector and a computer, and is characterized in that laser light is decomposed into two beams of laser pulses with different frequencies through the beam splitter, the two beams of laser pulses with different frequencies shot to a third-order nonlinear material at a certain angle, two beams of four-wave mixing (Raman) signal light beams which are different from incident laser in frequency and different in propagation direction, and the intensity of generated signal light directly reflects the time domain contrast of the incident laser. According to the invention, four-wave mixing signal light which does not coincide with an incident beam in frequency is directly acquired, the device is simpler and high in stability, and the used components and nonlinear dielectric material are economic and cheap.

Description

technical field [0001] The invention relates to an ultrashort laser pulse time-domain contrast measurement technology, which is a scanning ultrashort laser pulse time-domain contrast measurement method based on frequency non-degenerate four-wave mixing (or Raman effect) and a corresponding measuring instrument device . [0002] technical background [0003] The emergence of chirped pulse amplification technology in 1985 rapidly increased the peak power of laser pulses. High-energy laser pulses have important applications in the fields of laser fusion, particle laser acceleration, and high-energy radiation sources. With the increase of peak power of laser pulses , the parameter of laser pulse contrast is becoming more and more important. Laser pulse contrast is defined as the ratio of the intensity of the main laser pulse to the intensity of the noise signal at the leading edge of the pulse. If the peak intensity of the laser reaches 10 22 W / cm 2 , even with a contrast rat...

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Problems solved by technology

This device also has some shortcomings, including: 1) In order to obtain the third-order cross-correlation signal light, the device adopts a two-step design of frequency multiplication and frequency summing, that is, the third-order non-linearity is obtained through two second-order non-linear processes. Linear cross-correlation signal light, the device is more complex and the price of nonlinear crystal BBO is more expensive; 2), the energy of the third-order cross-correlation signal light obtained by first multiplying the frequency and then summing the frequency is relatively weak and its wavelength is in the deep ultraviolet range, which is very difficult for the detector The performance requirements are relatively high; 3), due to the frequency doubling and phase matching limitations of the frequency crystal, the wavelength range of the light to be measured is also limited

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