Polarization smoothing based on full Poincaré beams modulated by stress-engineered optics.

In laser-driven inertial confinement fusion (ICF) facilities, nonuniform laser irradiation can cause significant challenges, such as hydrodynamics instability and laser plasma instability, which hinder the success of fusion. This article presents a new idea for improving the uniformity of far-field laser irradiation through a method of single-beam polarization smoothing. The method involves modulating full Poincaré beams using stress-engineered optics made from fused silica. We designed a stress birefringence system and conducted opto-mechanical modeling and analysis on it. The article elaborates on the mechanism and principles of generating large-aperture full Poincaré beams by stress birefringence, as well as the mechanism of polarization smoothing by full Poincaré beams. Near-field polarization measurements were conducted to verify these mechanisms, and the effectiveness of this method in improving the uniformity of laser irradiation in the target area was evaluated through far-field optical tests.

Divergent beam-based method for measuring the detuning angles of a laser frequency converter.

We propose a method to obtain the detuning angles of a frequency converter by tripling the frequency of a divergent Gaussian beam. The frequency tripling process of the divergent beam was first simulated. It is found that the detuning angles of the frequency converter are linearly related to the position of the maximum light intensity point of the third harmonic laser. The corresponding experiment was conducted, and the results agreed well with the theoretical analysis. This method measures the detuning angles of the frequency converter in only one measurement and within 1 min. The detuning angle measurement errors of KDP and KD*P crystals are less than 10 µrad and 36.5-61.9 µrad, respectively.