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

Bumin K. Yildirim*, Hamza Kurt, Mirbek Turduev

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Recently, multilevel diffractive lenses (MDLs) have attracted considerable attention, mainly due to their superior wave-focusing performance; however, efforts to reduce chromatic aberration are still ongoing. Here, we present a numerical design and experimentally demonstrate a high-numerical aperture (∼0.99), diffraction-limited achromatic multilevel diffractive lens (AMDL), operating in the microwave range of 10–14 GHz. A multi-objective differential evolution (MO-DE) algorithm was incorporated with the three-dimensional (3D) finite-difference time-domain method to optimize the heights and widths of each concentric ring (zone) of the AMDL structure. To the best of our knowledge for the first time, in this study, the desired focal distance was also treated as an optimization parameter in addition to the structural parameters of the zones. Thus, MO-DE diminishes the necessity of predetermined focal distance and center wavelength by also providing an alternative method for phase profile tailoring. The proposed AMDL can be considered an ultra-compact and flat lens since it has the radius of 3.7λc and a thickness of ∼λc, where λc is the center wavelength of 24.98 mm (i.e., 12 GHz). The numerically calculated full width at half maximum values are <0.554λ and focusing efficiency values are varying between 28% and 45.5%. To experimentally demonstrate the functionality of the optimized lens, the AMDL composed of polylactic acid material polymer is fabricated via 3D-printing technology. The numerical and experimental results are compared, discussed in detail, and observed to be in good agreement. Moreover, the verified AMDL in the microwave regime is scaled down to the visible wavelengths to observe achromatic and diffraction-limited focusing behavior between 380 and 620 nm wavelengths.

Original languageEnglish (US)
Pages (from-to)2095-2103
Number of pages9
JournalPhotonics Research
Volume9
Issue number10
DOIs
StatePublished - Oct 1 2021

Bibliographical note

Funding Information:
Acknowledgment. H. Kurt acknowledges partial support from the Turkish Academy of Sciences. Authors would like to thank Jacob Engelberg from The Hebrew University of Jerusalem for his valuable comments and suggestions. H. Kurt acknowledges the financial support of KAIST Startup Funding (Project number G04200054).

Publisher Copyright:
© 2021 Chinese Laser Press

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics

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