A<sub>2</sub>S<sub>8</sub> glass films are shown to undergo changes in the refractive index under ultraviolet (UV) illumination and
annealing treatment, respectively. Under UV illumination, the maximum change in the refractive index of the
as-deposited A<sub>2</sub>S<sub>8</sub> is ~0.056; while under annealing treatment, it lies on and increases with increase of the annealing
temperature. In addition, the changes of the refractive index in the well-illuminated A<sub>2</sub>S<sub>8</sub> glass films after annealing are
not reversible until the annealing temperature is up to 160°C.The A2S8 channel waveguide fabricated by exposure to UV
illumination still exists after annealing of 130~160°C, and the refractive index differences between the areas of the
channel waveguide and the planar waveguide in this waveguide are 0.0120~0.0081. Light propagation experiment shows
that this A<sub>2</sub>S<sub>8</sub> channel waveguide has a light guide character with good quality and a low propagation loss of ~4dB/cm.