Because of the limited optical element aperture, damage threshold, gain bandwidth, and so on, the output capability of a
single laser beam is limited seriously. The coherent laser beam combining offers an excellent method to improve the
peak intensity which could be gotten greatly. Aiming at getting the general requirements of the coherent beam combining
for large aperture laser facilities, this work devotes to modeling the influences of the phase factors and spectrum factors
on the combine results. The effects of the phase factors, including the piston error and tip/tilt error, are studied
analytically and numerically. It is found that the expressions of the intensity in the focal plane can be written as three
parts, the scale factor, a point spread function (PSF), and a grid function (GF), for the ideal beam combining and beam
combining with piston error. Every part has its special physical meaning, and decides different characteristics of the
combined focus. For the beam combining with tip/tilt error, though the expression of focal spot intensity can not be
separated like the above situations, every part still has obvious physical meanings. The results show that the beam
configuration can not affect the Strehl ratio of the combined beam, but it influences the FWHM of the main peak and the
ratio of the main peak and the side peak. The piston error affects the grid function greatly, including its maximum value,
transverse translation, and shape. For the two beam combining, a piston error less than 2π/5 rad is suitable. For multibeam
combining, the standard deviation of the piston error should be no more than 2π/10 rad. The tip/tilt error affects the
superposition degree of the focal spots of the combined elements directly. A requirement of 0.5~1μrad for the standard
deviation of the tip/tilt error is adequate. The effects of the spectrum factors, including the longitudinal chromatism, high
order dispersion, and residual chirp, are studied analyzed. Results show that the above spectrum factors have significant
influences on the short pulse coherent beam combining, and must be controlled carefully when the pulse is shorter than
The paper summarizes the recent progress on the optical materials and components for the high power laser system in
China. The amplifier material, Nd glass, has been developed with continuous melt. Non-linear crystals, KDP/DKDP,
have been grown with rapid and traditional growth method. Fused silica and K9 glass has been achieved high quality.
Some potential materials for next generation high power laser system are also evinced in this summary.
A general method of designing multilayer dielectric (MLD) gratings for ultrashort pulse compressor is presented, which
is based on the integration of Fourier spectrum decomposition and rigorous modal method. Numerical calculations show
that the shape and energy of the -1<sup>st</sup> order reflected pulse is greatly dependant on the reflection bandwidth of the MLD
grating, which can be greatly improved by etching gratings into a MLD coating with broad reflection bandwidth. In order
to improve the damage resistant ability, the average intensity in the MLD grating is used as another criterion to optimize
the grating structure. The fabricated MLD gratings provide diffraction efficiencies higher than 95% at Litrrow angle of
51.2 degree for 1053nm short pulse. Damage tests show that 3.5J/cm<sup>2</sup> LIDT can be obtained under the irradiation of 12-
ns pulse light.
In the investigation of Inertial Confinement Fusion (ICF), the high power laser beam must be focused on the target (focus plane) given. In the ICF indirect drivers, the target fixed in a cavity is cylinderal, there are the Deuterium and the Tritium in the target, the experiment result relatives with the temperature radiated in the cavity, and the temperature relatives with the laser energy power incided. Thus, it is key that there must be enough of energy incided, and the energy runs out barely. So, to increase the laser energy incided, the focus spot should be very small. Base on the design of focus optical systems of the SHENGUANG serial facilities and the theory analyses, as the diffraction of the light, the laser beam passing through the optical systems gets a spot on the focus plane. In order to reduce the edge of the main spot or the focus spot size, we advance a method of dividing aperture of the focusing optical system, the diffraction theory of light shows that the diffraction main spot is reduced, it indicates that the method of dividing the aperture may be recommended.
In this paper we give a brief review of the fundamental acousto-optic interaction theory. Design and fabrication considerations for Multichannel Bragg Cell are studied. We designed and fabricated a four-channel LN/ZF-6 modulator which has 75 MHz center frequency, 15 MHz bandwidth and more than 10% diffraction efficiency.
With the Fresnel diffraction theory and Collins equation, the propagation of power spectral density (PSD) of wave-front with random spatial distribution is studied. The theoretical analysis for the propagation of PSD in some typical optical systems is concerned, and the detail simulant results are also given.
This paper introduces a new type of reflector mount array, which is designed for main amplifier of ICF Laser Driver in China. The whole system utilizes a special array structure, in compliance with the requirement of a small distance among each beam of the laser system. The one-body joint drive structure and a flexible structure ensure the system with high adjusting accuracy and stability. In addition, according to the characteristic of this system, the paper calculates the turning angle and accuracy of the flexible, which shows that the theoretical accuracy can reach 0.017', and the experiment results confirm this accuracy. The transmission error of one- body joint drive structure is analyzed in detail, and Finite Elements Method is used to optimize the support structure in order to lessen the deformation of the reflector.