Study On Grooves Misalignment And Beam Characteristics Of Parallel Grating Pair

High power and ultrashort pulse laser, which has been applied in many fields, such as high field physics and ultrafast optics, and whose key technique is chirped pulse amplification(CPA), is always the focus of study. The parallel grating pair with the capability of compensating dispersion can be used as compressor in CPA. So the study of parallel grating pair is related to the technique of high power and ultrashort pulse laser, and has great significance for applications.Firstly, the system of parallel grating pair, in which the grating grooves is unparallel while the grating surfaces is parallel, has been studied with the tri-dimensional ray-tracing method. The 2nd and 3rd dispersion of the system and the relative errors of dispersion with the condition that the grating is strictly parallel were calculated by the group delay of light passing through this system. The received position's variation of the light on the received surface was achieved, and its variations with the incident angle were analyzed. These results pr6vide references for adjusting system.Secondly, the propagation equation of monochromatic beam passing the parallel grating pair has been deduced using the theory of plane-wave angular spectrum and the first-order diffraction equation of grating. This equation is adapted to any shape's input beam and can be easily realized using fft arithmetic. The propagating characteristics of Supper-Gaussian beam have been simulated, and the result shows the dissymmetry effect of the parallel grating pair on the beam vertically and horizontally. Then, the effective distance expression of angular spectrum along optical axis has been introduced by comparing this equation with the free propagation equation. By analyzing this expression, the critical incident angle has been found and the received beam may be narrowed relative to free propagation when the incident angle of the optical axis is bigger than this angle. Meanwhile, this equation has been simplified when the spatial bandwidth is narrower. With the simplified equation, the expression of received beam has been achieved for Gaussian beam. At last, the propagation equation of pulse beam has been deduced.