Study Of Stability Of Large-size Holographic Interference Optical Field

Pulse compression gratings is the key element in chirped pulse amplification(CPA) technology. The grating aperture is reached meter level with the output energy of short-pulse laser systems improve. Holographic recording technology is the main technology to fabricate large aperture pulse compression gratings. The control study of profiles of photoresist grating masks is of great significance to fabricate large aperture pulse compression gratings. The stability of large-size holographic interference optical field has been studied systematically in this article. Main research results are as follows:1. The characterization of stability of large-size holographic interference optical field have been studied. The stability of large-size holographic interference optical field which effect on holographic recording has been studied. The patterns of movement of interference fringes have been studied, which impact on the contrast of interference fringes. Laser intensity change, laser wavelength change and substrate temperature change which effect on the interference fringes have been studied. In order to control large-size holographic interference optical field, the control mode of stability of three-dimensional fringes has been given.2. The photoresist exposure characteristics has been studied. In order to get the absorption rate variation curve, the experiment of the average absorption rate changing with the exposure dose at different photoresist thickness has been carried out, and the experimental curves at different photoresist thickness are obtained. The absorption rate variation curve has been simula ted through theoretical inversion. The developing characteristics of the Shipley9912 photoresist has been studied. The experimental curves at different developing time are obtained. Combined with the photoresist absorption rate, the absorption rate variation curve has been simulated through theoretical inversion.3. In order to obtain the relationship between stability of fringes and grating mask groove, a new nonlinear exposure model is proposed, which is based on the absorption rate changing with the exposure dose. In order to precise control the photoresist grating mask groove, the relative calculation formula of the nonlinear exposure model is given for analysis the exposure of the photoresist grating in the holographic recording process. Combined with the development model, the grating mask groove has been simulated under different stability of interference fringes. The experiments of different space-frequency holographic grating have been carried out. The simulated grating mask structure agrees with the experimental results. The new nonlinear exposure model is of great significance to improve the control precision of holographic grating mask.