Total internal reflection holographic recording in chalcogenide glass films

The results of holographic recording by the prism method are presented. The Stetson scheme is employed to obtain two slanted diffraction gratings using the 488 nm line of an Ar 2+ laser. In this set-up, one of the recording beams suffers total internal reflection at the sample-air interface. Thus two Bragg gratings with high and low spatial frequencies are simultaneously recorded. The pitches of these gratings are 96 nm and 444.1 nm, respectively. Fresh as-deposited As 2 S 3 films with 0.5, 0.87 and 2.07 μm thickness are used. This is an intermediate case between thick gratings and those recorded in a very thin layer, which represents the Nassenstein set-up. In the last scheme, the grating is situated in a layer thinner than 30 nm and the surface interactions play a major role. Upon increasing the thickness, the boundary in which the total internal reflection takes place is changed as well as the recorded diffraction pattern. This is due to the high refractive index of the recording medium. In the present work, the differences in the recording kinetics and the properties of the recorded gratings depending on the thickness are examined. The angle selectivity and polarization sensitivity are studied. A better-expressed Bragg behaviour is observed for the thicker samples. The Klein parameter is evaluated for gratings recorded in samples of different thickness.