This work focused on the newly designed poly(methyl methacrylate) (PMMA) doped in Rhodamine B (Rh-B) dye on a glass substrate for wide-scale applications. In the current study, we have examined the influence of adding different concentrations of Rh-B dye to PMMA on the optical properties of the composite samples, Rhodamine B dye-doped PMMA thin films /glass substrate. Utilizing the spin coating technique, we have prepared uniform thin films. We have studied the structural characterizations of the samples via XRD. The samples displayed a hump which proves that the structure of the investigated composites is noncrystalline. Utilizing absorption, reflection, and transmission spectra of the specimens, the optical parameters like absorption coefficient, dielectric function, and refractive index have been calculated. Moreover, the impact of the impurity of the dye on these parameters has been discussed. Furthermore, the calculated bandgap of the samples reduced by raising the concentration of dye impurity. The CUT-OFF/limiting characteristics of UV–vis laser for the tested samples with different proportions of the dye have been examined utilizing a He-Ne laser running at 532 and 632.8 nm. The results depicted the partial blocking of the incident laser beam at 532 nm. The prepared Rh-B/ PMMA films can be applied in broad range applications