Inverse designed achromatic flat lens operating in the ultraviolet

Abstract

We demonstrate an inverse designed achromatic, flat, polarization-insensitive diffractive optic element, i.e., multilevel diffractive lens (MDL), operating across a broadband range of UV light (250 nm -400 nm) via numerical simulations. The simulated average onaxis focusing efficiency of the MDL is optimized to be as high as ~86%. We also investigate the off-axis focusing characteristics at different incident angles of the incoming UV radiation such that the MDL has a full field of view of 30˚. The simulated average off-axis focusing efficiency is ~67%, which is the highest reported till date for any chromatic or achromatic UV metalens or diffractive lens to the best of our knowledge. The designed MDL is composed of silicon nitride. The work reported herein will be useful for the miniaturization and integration of lightweight and compact UV optical systems.

Ultra-compact, high-numerical-aperture achromatic multilevel diffractive lens via metaheuristic approach

“…3(c  is the wavelength of the center frequency ( 12GHz), which is 24.98 mm. The average value of the broadband F  is equal to 13.49 mm which means that the average shift in focal lengths equals to 2.38% [25]. All the presented results verify that the implemented MO-DE algorithm satisfactorily suppresses the focal shift over a broadband range.…”

“…To verify broadband operation functionality of the designed AMDL, the maps of the experimentally measured cross-sectional intensity profiles on the optical axis and on the lateral direction of focal point are presented in Figs. 5(a  is equal to 12.85 mm which means that the average shift in focal distances equals to 7.01% [25]. As can be seen from Fig.…”

“…In the MDL structures, each zone plays an important role on chromatic aberration-free focusing effect if the zone's parameters are adjusted properly [22]. Hence, the various optimization and inverse design methods have been exploited to obtain appropriate MDL parameters for efficient focusing [23][24][25][26]. One of the important design characteristics of the metalenses and MDLs is their numerical aperture (NA) value which is a function of focal length, the radius of the lens, and the refractive index of the medium.…”

Planar metasurface-based concentrators for solar energy harvest: from theory to engineering

“…5(a), the solar radiation covers the ultra-broad bandwidths from the NIR region (from 780 nm to 2526 nm) to the deep-UV (DUV) range (from 190 nm to 280 nm) [18,176,177]. According to the aforementioned introduction of the building materials, a meta-lens that is formed using different materials generally operates at the corresponding spectrum, and thereby, we will introduce the high-focusing-efficiency optical meta-lenses in terms of their working wavelengths, including the NIR [169,174,[178][179][180][181][182], visible [134,152,164,165,[183][184][185][186][187], and UV bands [146,148,149,[188][189][190][191][192][193]. The focusing efficiency is defined as the optical power confined within a focal spot divided by the corresponding incident power.…”

Super-resolution imaging with an achromatic multi-level diffractive microlens array

“…We recently showed that MDLs have equal or better performance when compared to metalenses, which are harder to design and manufacture [11]. MDLs have already been demonstrated in the ultraviolet [12], visible [13], near infrared [14,15], short wave infrared, [16] long-wave infrared [17], THz [18], and microwave [19] bands. Magnification in an imaging system was also demonstrated by coupling two MDLs [20].…”