Development of gradient index microlenses for the broadband infrared range.

The development of gradient index free-form micro-optic components dedicated to the mid-infrared range is challenging due to the lack of appropriate technology. We propose a method for developing gradient index components for broadband infrared range beyond the transmission window of silicate glass based on nanostructurization using a stack-and-draw fiber drawing technique. A proof-of-concept microlens is developed and verified experimentally in the wavelength range 1.5-4.3 µm. The microlenses are composed of a set of nanorods with a diameter of 940 nm made of a pair of SiO