Ultra-broad band and tunable optical limiting based on photo-refraction of PbSe quantum dots

Abstract

Optical limiting devices are critical in protecting optical sensors and the human eye from irreversible damage, which block high-intensity laser radiation while allowing low-intensity laser radiation. Basically, there are three types of optical limiters based on absorption, refraction and scattering. Absorption-based optical limiters may be more easily damaged than refraction-based ones due to absorbing high energy. Scattering-based optical limiting effect is relatively weak when the particle size is small. In this paper we report a PbSe quantum dots-based optical limiter, which refracts lights off the transmission path to achieve optical limiting. The nonlinear refractive indices and thermo-optic coefficients of PbSe quantum dots-doped films with different doping concentrations at 405 nm were obtained by using the Z-scan technique. As increasing the input light radiation the refractive index of the doping sample decreases, which makes light beam more divergent and keeps the remaining light intensity stable. As of that PbSe quantum dot has wide-band absorption, the PbSe quantum dot-based optical limiter works from blue to near-infrared. By changing the doping concentration the optical limiting effect could also be adjusted.