Optical Limiting Properties of DNA Biopolymer Doped with Natural Dyes.

The high-power lasers have important implications for present and future light-based technologies; therefore, the protection measures against their high-intensity radiation are extremely important. Currently, a great deal of interest is directed towards the development of new nonlinear optical materials for passive optical limiters, which are used to protect the human eye and sensitive optical and optoelectronic devices from laser-induced damage. Biopolymers doped with natural dyes are emerging as a new class of optical materials with interesting photosensitive properties. In this paper, the optical limiting capability of deoxyribonucleic acid bio-polymer functionalized with Turmeric natural dye has been demonstrated for the first time, to the best of our knowledge. The experimental investigation of the optical limit has been done by the Intensity-scan method in the NIR spectral domain at the important telecommunication wavelength of 1550 nm, using ultrashort laser pulses (~120 fs). Several optical properties of this natural dye are presented and discussed. The values of the optical transmittance in the linear regime, the saturation intensity of the nonlinear transmittance curves, and the coefficient of the nonlinear absorption have been determined. The influence of the DNA biopolymer and natural dye concentration on the optical limiting properties of the investigated biomaterials is reported and discussed. The photostability and thermal stability of the investigated solutions have also been evaluated by monitoring the temporal decay of the normalized absorption spectra under illumination with UVA light and heating, respectively. Our results evidence the positive influence of the DNA, which embeds Turmeric natural dye, on the optical limiting functionality itself and on the photostability and thermal stability of this novel material. The performed study reveals the potential of the investigated novel biomaterial for applications in nonlinear photonics, in particular in optical limiting.