Optical limiting studies of organic semiconductor molecule with carbon nanotube addition

Recent interest in thiophene-based molecules for nonlinear optics (NLO) and optical limiting studies is due to their
good solution processability and optical modulation. In order to overcome weakness of thiophene based optical limiter at 532 nm wavelength, versatile carbon nanotubes (CNT) are introduced into the freeform thiophene solution. This paper investigated the role of multi-walled carbon nanotubes (MWCNT) addition in thiophene's third-order NLO
characteristics at 532 nm cw laser as equal weight ratios composite. CN T is chosen because of its broadband NLO
property, unique structural and electronic properties, and tackling CNTs' dispersion instability can optimize its full
potential in photonics and laser applications. Prior to the optical limiting measurement, surface interactions between
both materials were analyzed using UV-vis and Raman spectra. Significant improvement of optical limiting at 532 nm was discussed using nonlinear refraction {HT) and absorption {ff) obtained from open and closed aperture z-scan
measurements, respectively. It was found that absorption related nonlinearity increased drastically after CNT addition that contributed to a more stable optical limiting behavior at this energy. The reverse saturable absorption
characteristics of this organic semiconductor molecule can be exploited as laser protective coating and in other broad
areas of materials, optoelectronics and photonics related to 532 nm laser applications.