The invention discloses a photoinduced stable nonlinear
sulfur film, and a preparation method thereof, and belongs to an
optical film and a
nonlinear optical material. The
chemical composition of the film is GexAsySzSe(100-x-y-z), wherein x is smaller than or equal to 14 and greater than or equal to 10; y is smaller than or equal to 28 and greater than or equal to 20; z is smaller than or equal to 50 and greater than or equal to 16. A vacuum thermal
evaporation method is adopted in preparation of the film; the vacuum degree is 10<-4> to 10<-6>
torr; the
evaporation rate is 3-20 nm / min; the
refractive index of the
sulfur film prepared by the method at
wavelength of 1.55 microns is 2.20-2.56; the
refractive index change of the film under thermal annealing and sub-
band gap illumination is 10<-3>; an optical
band gap is 1.98-2.48ev; the loss of the film at the
wavelength of 1.55 microns is smaller than 0.2 dB / cm; the third-order
nonlinear refractive index at the
wavelength of 1.55 microns is 2.0-6.0*10<-14> cm<2> / W; no significant two-
photon is absorbed; a
laser-damaged threshold is greater than 200 GW / cm<2> (5.3 microns, 150fs, 1kHz). The photoinduced stable nonlinear
sulfur film has the advantages that 1, the photoinduced
refractive index change is tiny, and the optical performance of an apparatus is stable; 2, the anti-
laser damage threshold of the film is high, and application of the apparatus in the field of
nonlinear optics is facilitated; 3, the composition and the refractive index of the film obtained by
vacuum evaporation are consistent with those of adopted block raw materials, and the films produced in different batches are consistent in performance, and easy to control.