A novel optical limiter and UV-Visible filters made of Poly (vinyl alcohol)/KMnO4 polymeric films on glass-based substrate

A poly (vinyl alcohol) polymeric films doped with various stages of concentrations (0, 0.037, 0.185, 0.37, 1.85 and 3.7 wt%) of KMnO4 salt were prepared by casting technique on glass substrate as a new optical limiting and laser filter application. Their structures, molecular complex formation and the morphology of the surface are analyzed by using XRD (X-ray diffraction), FTIR (Fourier transform-IR), and SEM (scanning electron microscopy), while the optical band gap as well as limiting characteristics is determined via UV-Vis spectroscopy, and optical limiting set-up for two laser sources, respectively. As a result of the increment of KMnO4 salt percentage inside the PVA polymer matrix, there is a significant decrease in the number of chain domains with a specific alignment (crystallizing degree) is observed through XRD diffraction and confirmed via Gaussian fitting and Fityk 0.9.8 software. FTIR spectra shows the complex interface interaction between KMnO4 and PVA. The numerical density as well as the size of the particles was increased as clearly seen in SEM images. In addition, the energy gap is markedly decreased from 3.6 eV to 1.1 eV for Pure PVA and 3.7 wt% of KMnO4 doped PVA (KMPVA5), respectively, on the glass substrate sample. The incident light was completely blocked in the UV range and extended to 555 nm in the visible region for the highest doping of KMnO4 in PVA. Moreover, a sharp decrease in the output and normalized power of the two laser sources via KMPVA5 film were detected. Therefore, for low cost optical limiting and laser filter technology, the PVA with the high concentration level of KMnO4 is considered as a promising candidate.