Negative thermo-optic coefficients and optical limiting response in pulsed laser deposited Mg-doped ZnO thin films

Abstract

Thermo-optic properties and optical limiting characteristics are investigated in pulsed laser deposited Mg-doped ZnO thin films by performing a Z-scan experiment in the off-resonant regime using a CW He–Ne laser source. Optical limiting studies in these thin films lead to a conclusion that reverse saturable absorption is the major mechanism for optical limiting properties in these films and nonlinear refraction is caused due to the thermal lensing effect. Negative thermo-optic coefficients were observed, indicating potentiality for athermalization, required to counter the effect of thermal expansion. Sufficiently large thermo-optic coefficients and good optical limiting response suggest the utility of MgZnO films for thermo-optic switches and optical limiting device applications.