NONLINEAR OPTICAL PROPERTIES AND OPTICAL POWER LIMITING OF POLY (3HT- Co - Th) - PMMA POLYMER BLEND FILMS

Poly (3 - Hexylthiophene - Co - Thiophene) copolymer was prepared using the addition polymerization method and poly (3HT- Co - Th) – PMMA polymer blend films were prepared using the casting method. The nonlinear optical properties and the behavior of the optical power limiting of the prepared films were studied using the z - scan technique for different weight ratios of the copolymer poly (3HT- Co - Th). In the present work, a continuous wave (CW) diode - pumped solid - state laser (DPSSL) of wavelengths 532 nm was used for the irradiation of the prepared film samples. The nonlinear optical parameters such as, the nonlinear refractive index (n2), the nonlinear absorption coefficient (β), and the third - order nonlinear optical susceptibility (χ (3)) of the polymer blend poly (3HT- Co - Th) - PMMA films were determined for different weight ratios of the copolymer poly (3HT- Co - Th). It is observed that the polymer blend poly (3HT - Co - Th) - PMMA films exhibit saturable absorption (SA) and self - defocusing effects, and this gives an indication that both, the nonlinear refractive index (n2) and the nonlinear absorption coefficient (β), have negative values. The obtained results indicate that the prepared polymer blend poly (3HT - Co - Th) - PMMA films are promising materials and can be considered as suitable materials for different optical and electronic applications.