Time dependent diffraction ring patterns in bromothymol blue dye doped PMMA film under irradiation with continuous wave green laser light

Abstract

Diffraction ring patterns are generated in bromothymol blue (BTB) doped poly methyl methacrylate (PMMA) film with the aid of visible light from a solid state laser of Gaussian distribution. Temporal evolution of patterns i.e. the number of rings increases as time elapse is observed. Based on the experimental findings, change in refractive index (∆n) effective nonlinear refractive index (n 2) and variation of refractive index with temperature (dn/dT) have been obtained as 0.0025, 1.45 × 10−6 cm2 W−1, 1.69 × 10−5 K−1 respectively. Obtained results suggest the possibility of using BTB doped PMMA in data storage, recording and holography.