Investigation of third-order nonlinear optical properties of nanostructured Ni-doped CdS thin films under continuous wave laser illumination

• Published in: Journal of materials science. Materials in electronics 2019-04, Vol.30 (7), p.6993-7004
• Main Authors: Bairy, Raghavendra, Jayarama, A., Shivakumar, G. K., Radhakrishnan, K., Bhat, Udaya K.
• Format: Article
• Language: English
• Subjects: Absorptivity; Cadmium sulfide; Characterization and Evaluation of Materials; Chemistry and Materials Science; Constraining; Continuous wave lasers; Doping; Energy gap; Field emission microscopy; Materials Science; Morphology; Nickel; Nonlinear optics; Optical and Electronic Materials; Optical properties; Photon absorption; Pyrolysis; Refractivity; Scanning electron microscopy; Thin films
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-019-01017-5

We report the third-order nonlinear optical (NLO) properties and optical limiting (OL) thresholds of pure CdS and Ni-doped CdS thin films have been investigated with the Z-scan technique under continuous wave laser excitation. Nanocrystalline CdS thin films with various doping concentrations of Ni (0%, 1%, 3%, 5% and 10 at.%) are prepared by spray-pyrolysis technique. XRD patterns reveal that all the prepared films are polycrystalline and the incorporation of Ni does not lead to major changes in the crystalline phase of Cd 1−x Ni x S thin films. The surface morphology of the prepared films is impacted by the Ni-doping and is indicated by Field Emission Scanning Electron Microscopy (FESEM) images. With an increase in Ni-doping concentration, the energy band-gap value decreased from 2.48 eV to 2.23 eV. From the Z-scan data, it is observed that the material show strong two-photon absorption (2PA) and with an increase in Ni-doping concentrations from 0 to 10 at.%, the nonlinear absorption coefficient (β) are enhanced from 0.92 × 10 −5 to 4.46 × 10 −5 (cm W −1 ), nonlinear refractive index ( n 2 ) from 0.2967 × 10 −9 to 0.1297 × 10 −8 (cm 2  W −1 ) and thereby the third-order NLO susceptibility (χ (3) ) values also increased from 1.7075 × 10 −6 to 7.4743 × 10 −6 (esu). OL characteristics of the prepared films are studied at the experimental wavelength. The results propose that the Cd 1−x Ni x S film is a capable material for nonlinear optical devices at 532 nm and optical power limiting applications.