<title>Real-time splitting behavior of stratified holographic optical elements</title>

Abstract

A new method for the preparation of stratified light-sensitive film is developed and the stratified gratings are recorded in the film. The real-time splitting behaviour concerning angular sensitivity and diffraction properties as a function of the normalized buffer-layer thickness in this stratified holographic optical gratings have been analyzed. It is found that by optimizing the combination of modulation of grating, spatial frequency and the total thickness of grating, the changeable number of output beams can be obtained. . INTRODUCTIONRecently the stratified grating ( S G ) has received an increase in interest and attention due to its high diffraction efficiency and its distinct diffraction properties .The stratified volume holographic optical elements comprisea proposed class of novel diffraction structures in which multiple layers of a thin holographic material are interleaved with optically homogeneous buffer layers. In addition, the relation between the diffraction efficiency and the incident angle of the readout beam has a strict periodic selectivity. The stratified gratings used as beam splitters can be easily realized with simple recording setups and high diffraction efficiencies. Although the beam splitters can be made by several methods, each of them has its shortcomings. One of the authors of the paper reported a new method for making stratified light sensitive films and double -layer stratified gratings were fabricated with the confact-printing method with partial coherent light . In the fabrication , cellulose triacetate (CTA)film is used as the substrate .Without the use of any coating , the sensitive layers of the film are produced simultaneously on both sides of the film. The refractive indexes of the sensitive layers are approximately equal to that of the buffer, so the diffraction efficiency of the resultant stratified gratings may be increased to some extent. Based on the new stratified gratings of the film, several beam splitters with 2, 3, 4 and 7 fan-outs and higher than 80% total diffraction efficiencies are realized. In this paper. the real-time splitting behaviour concerning angular sensitivity and diffraction properties as a function of the normalized buffer-layer thickness in the new stratified holographic optical gratings hase been further analyzed. It is found that by optimizing the combination of modulation of grating, spatial frequency and the total thickness of grating, the changeable number of output beams can be obtained. 2. ANGULAR SENSITIVITY * supported by the National Natural Science Foundation of China 'Tel:86 027 87684026, Fax:86 027 87882661 SPIE Vol. 3559 • 0277-786X/981$10.00 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/23/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx