3rd order optical nonlinearity enhancement of halochromic phenol red dye immobilized in PVA/silica hybrid host matrix

In this study, we investigate the third-order nonlinear optical properties of phenol red (PR) solutions and their hybrid composites, analyzing a PR solution with a pH of 7.56, a zwitterionic PR solution (PR z ) with a pH of 1.52, and a PR-doped PVA/silica (PR-PS) hybrid composite made using an acid-catalysed sol-gel method and drop-casting technique. The PR-PS thin film exhibits a smooth and homogeneous surface, with a root mean square roughness (RMS) of 0.816 nm and an average roughness, Ra of 0.648 nm. FESEM was employed to analyze the surface morphology and thickness of the thin film, which was found to be approximately 80 µm. UV-vis analysis demonstrates that PR in the matrix is in its zwitterionic form, with absorption peaks at 450 nm and 515 nm. The PVA/silica hybrid matrix exhibits an enhancement in third-order nonlinear susceptibility, χ (3) by 83.94%. Moreover, our finding also indicates that the PR-PS hybrid composite’s β being being 79.09% and 99.37% larger than that of the PR and PR z samples, respectively. These results suggest that the PR-PS thin film is a promising material for photonic applications, such as nonlinear optical switching devices and optical limiting applications, due to its enhanced nonlinear optical properties. Graphical Abstract The diagram above shows the method used to synthesize resulting phenol red (PR) dye immobilized inorganic-organic hybrid matrix along with the results from its cross-sectional image from FESEM, AFM, nonlinear absorption and refraction results from Z -Scan.