Optical second order nonlinearity in ultraviolet poled chalcogenide thin films

Abstract

The second order optical nonlinear susceptibility measurement is done in (GeSe 3.5 ) 14) and Zn x S y Se 100-x-y (x=2, y=28; x=4, y=20; x=6, y=12; x=8, y=4) chalcogenide thin films. Thermal evaporation technique is used for the preparation of thin films. The dielectric constant at incident and second harmonic wavelength is calculated using BPARAV^computer software. The large second order nonlinearity is induced through ultraviolet poling by applying a dc electric field and irradiating with nitrogen laser at 337 nm. Thin film is irradiated with~532 nm wavelength of Nd: YAG laser and second harmonic signal at~266 nm wavelength alongwith incident light is obtained in reflection that is separated from~532 nm using a suitable optical filter. Second order nonlinear susceptibility is estimated by measuring the intensity of reflected beam of second harmonic signal that is found to increase with increase in Bi and Zn content in (GeSe 3.5 ) 100-x Bi x , and Zn x S y Se 100-x-y chalcogenide thin films, respectively. The induced second order optical nonlinearity shows the use of chalcogenide thin films in wavelength conversion and active devices.