Kramers-Kronig calculations for linear and nonlinear optics of nanostructured methyl violet (CI-42535): New trend in laser power attenuation using dyes

In this work, nanostructured methyl violet-10B (MV-10B) thin films of various thicknesses were coated on glass substrates by a low-cost spin coating method at different rpm. The structural analysis of nanostructured MV-10B thin films was carried out by X-ray diffraction and atomic force microscope. Optical measurements were carried out, and the direct band gap of MV-10B films was estimated. The study showed that the prepared MV-10B thin films act in the same manner as that of conventional direct bandgap semiconductors. From optical studies, the sample exhibited bandpass filter characteristics in IR range from 700 nm to 900 nm and in the visible range centered around 408 nm. Also, the sample absorbs or attenuates the range of wavelengths in the visible spectrum between 470 and 650 nm creating a good absorption band valley making a CUT-OFF laser filter. Optical constants such as refractive index (n) and extinction coefficient (k) were computed using Kramers-Kronig relations. The real and imaginary components of dielectric constant were calculated on the basis of polarization of light when it is impinging on semiconductors. Nonlinear index of refraction and susceptibilities were estimated by linear refractive index dispersion principles. Optical limiting studies showed that the MV-10B thin films are very good optical limiters even at low thickness. The MV-10B showed a laser attenuation behavior for He-Ne and green lasers. The obtained results suggest that the newly designed thin films are the promising candidate in different applications.