Pulsed laser deposited Zn1-xTixO (0.000≤x≤0.050) thin films for tunable refractive index and nonlinear optical applications

In the present paper, a systematic study on the structural, linear and nonlinear optical properties of Zn1-xTixO (0 ≤ x ≤ 0.050) thin films is documented. The thin films are grown onto fused silica substrate via pulsed laser deposition technique employing 2nd harmonic of a Q-switched Nd:YAG laser (532 nm, 10ns, 10 Hz). The crystallinity of the film is observed to be increased initially up-to x = 0.02 and then decreased for higher values of x. A small variation in band gap energy is observed in the Zn1-xTixO thin films with x which is mainly due to the Burstein Moss effect followed by the weak quantum confinement effect. The third order optical nonlinearities in the films are experimentally recorded using modified z-scan technique under cw He:Ne laser (λ = 632.8 nm) illumination. The nonlinear optical coefficients; β and n2, are observed to be in the range of 1.1-6.0 cm/W and (1.0-4.1) × 10−4 cm2/W, respectively. The maximum value of β (6.0 cm/W) and n2 (4.1 cm2/W) are observed in the Zn1-xTixO film having x = 0.02. These studies suggest that an optimum concentration of Ti content in ZnO is required for the enhancement in nonlinear optical behavior.