Publication
Development of gradient index microlenses for the broadband infrared range |
Kasztelanic R., Filipkowski A., Pysz D., Nguyen H.T., Stepien R., Liang S., Troles J., Karioja P. and Buczynski R. |
Optics Express30(2), 2022, 2338-2352, 10.1364/OE.448461 |
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 SiO2-PbO-Bi2O3-Ga2O3 based glasses ordered into the preliminary calculated binary pattern. The pattern forms effectively continuous parabolic refractive index distribution for infrared range according to Maxwell-Garnett effective medium model. The development of individual microlenses with a diameter of 118 µm and focal length of 278 µm at the wavelength of 3.75 µm are reported. A large array of 737 microlenses with an individual diameter of 125 µm and focal length of 375 µm is also presented and analyzed.