Thin films of chalcogenide vitreous semiconductors of the As-S-Se system exhibit both reversible and ineversible photo-strnctural transfonnations. Due to this they are promising materials as photoresist as well as registration media for recording of different kinds of diffraction elements for application in optoelectronics and microelectrnnics. For {As4S3Se3)i-x:Snx (x = 0 + 10 at. %) thin films (d:::::: 2 mkm) the photo-darkening effect induced by laser beam illumination (l = 532 nm) was studied. It was shown that the relaxation of photo­darkening TITo=f(t) in amorphous (As4S3Se3)i-x:Snx thin films can be described by the stretch exponential function T(t)/T(O) = A0+Aexp[-(t-t0)Jr/1-f]). Here tis the exposure time, r is the apparent time constant, A - characterizes the exponent amplitude, to and Ao are the initial coordinates, and a is the dispersion parameter (0 < /3 < 1). The dependencies of set of parameters values of stretch exponential function both on film thickness and Sn concentration were investigated. Diffraction gratings with grating period of A = 1 µm were optically recorded at 1 = 532 run. The monitoring of the intensity of first order diffracted laser beam (l = 650 nm) during the recording procedure was used. The dependence of diffraction efficiency (7/) on Sn concentrntion was investigated. Its value increased with increasing of Sn concentrntion up to 6.0 at. % Sn and then decreased at higher Sn concentration. For amorphous As4S3Se3 thin films the dependence of the diffraction efficiency on film thickness was investigated as well. The maximum value of diffraction efficiency was obtained for the films of diffraction efficiency was obtained for the films of thickness about L::::: 4.0 µm (Fig. I, curve 2) and was about 9.8 %. Similar dependence of diffraction efficiency was earlier obtained for amorphous As60Se40 thin films [ 1]. In the amorphous As4S3Se3 thin films the electron beam recording of diffraction gratings with grating periods of 1 µm and 2 µm was caITied out. Diffraction efficiency was measured in transmittance mode at nonnally incident He-Ne laser beam (0.633 µm). Dependences of diffraction efficiency on dose of inadiation (q) were studied. Maximum values of the first order diffraction efficiency were about 0.5% and 3.5 % for gratings periods of 1 µm and 2 µm, respectively. A sector of sha1p increasing of diffraction efficiency with inadiation dose was observed on the curve 'f/(q) for grating period of 2 µm. For diffraction gratings of both grating periods recorded at low inadiation doses the effect of enhancing of diffraction efficiency caused by unifonn laser beam inadiation (tc = 633 nm) was observed. This effect can be attributed to increasing of depth of refraction index modulation, caused by non-unifonn light abso1ption which is evidently stronger in the e-beam iirndiated areas of recorded gratings than in non-ii-radiated ones.