Enhanced nonlinear optical absorption and optical limiting performance of nanoparticles embedded lanthanum alkali borate glasses bearing holmium ions at off–resonant spectral excitation

Abstract

Herein, the efficacy of silver nanoparticles on the nonlinear optical features of holmium ions bearing melt–quenched borate–based glasses has been investigated. The silver nanoparticles free holmium doped glass possesses weak nonlinear absorption and high optical limiting threshold in the near–infrared spectral range. It was observed that the nonlinear absorption and optical limiting performance were significantly improved upon co–doping of silver NPs in the lanthanum alkali borate glasses. The linear optical absorption measurements partially confirmed the presence of silver nanoparticles in the prepared glasses. The electron microscopic measurements disclosed the evidence for the formation of spherically shaped silver nanoparticles in the glasses. The nonlinear optical and optical limiting features were ascertained by the open aperture Z–scan technique in off–plasmon excitations by benefitting femtosecond laser pulses fired at kHz repetition rate. The outcomes endorse that the high AgCl loaded lanthanum alkali borate glasses are useful in suppressing the high energy near–infrared laser radiation for the protection of sensitive optical devices (e.g., human eye) from the laser damage.