Method for enhancing optical parametric amplifier output magnified signal light impulse and beam quality

Abstract

The invention pertains to the technical field of laser, in particular to a method for improving the quality of light pulse and light beam of amplified signals output from an optical parametric amplifier. In the process of optical parametric amplification (OPA) or optical parametric chirped pulse amplification (OPCPA), the method utilizes an OPA device to improve the quality of the light pulse and the light beam of the amplified signals through controlling phase shifts of signal light in the pump light direction. The method avoids influences of spatial walk-off and group velocity mismatch, relaxes requirements on the quality of pump light, and improves the quality of the light pulse and the light beam of the amplified signals; thereby the method is suitable for a high-energy OPA device or a high-energy OPCPA device.

Description

Technical field [0001] The invention belongs to the field of laser technology, and specifically relates to a method for improving the quality of the output and amplified signal light pulses and beams of an optical parametric amplifier device. Background technique [0002] The high-intensity ultra-short pulse output by the high-energy laser device creates extreme physical conditions, which can be used to study new phenomena in the field of strong field physics, including: "fast ignition" inertial confinement nuclear fusion, high energy density physics, laboratory celestial bodies Physics, super acceleration of charged particles, etc. These important applications not only require laser pulses with high energy but also ensure good pulse quality. Chirped Pulse Amplification (CPA) or Optical Parametric Chirped Pulse Amplification (OPCPA) is an important means to obtain ultra-strong and ultra-short laser pulses. With a high-energy neodymium glass laser as the pump source, the OPCPA sys...

AI Technical Summary

Problems solved by technology

However, in these high-energy OPCPA systems, due to the large aperture of the OPA crystal and the use of birefringent phase matching, there is a spatial walk-off between the pump light, the signal light, and the idler light.

In addition, the pump light with megajoule pulse energy usually does not reach the diffraction limit (10-20 times the diffraction limit), and its own beam quality is relatively poor

The phase shift in the optical parametric amplification process will cause the non-ideal phase distribution of the pump light to be transferred to the signal beam, which will seriously affect the quality of the amplified signal beam

On the other hand, the study of physical experiments puts forward very high requirements on the pulse quality (signal-to-noise ratio), requiring a "clean" pulse front, but in the current high-power laser system, the problem of signal-to-noise ratio has not been well resolved good solution

But in the time domain, simply adjusting the structure of the crystal itself cannot compensate for the group velocity mismatch in the OPA crystal (R.J.Gehr, R.W.Kimmel, and A.V.Smith, Simultaneous spatial and temporal walk-off compensation frequency-doubling femtosecond pulses inβ-BaB 2 o 4 .Opt.Lett.1998, 23:1298-1300), so the phase control of the signal light pulse cannot be realized

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