High efficiency nanohole based immersion metalens for light concentration

Nazmi Yilmaz; Ramazan Cetin; Ahmet Sozak; Eray Yasan

doi:10.1117/12.2594114

6 August 2021 High efficiency nanohole based immersion metalens for light concentration

Nazmi Yilmaz, Ramazan Cetin, Ahmet Sozak, Eray Yasan

Proceedings Volume 11795, Metamaterials, Metadevices, and Metasystems 2021; 117952C (2021) https://doi.org/10.1117/12.2594114
Event: SPIE Nanoscience + Engineering, 2021, San Diego, California, United States

Conference Poster

Abstract

Design and performance analysis of a high efficiency, nanohole based, polarization-insensitive, all-dielectric, immersion metalens is presented, which is to be monolithically integrated into a backside illuminated HgCdTe based photodetector with CdZnTe (4%) as the substrate material for MWIR (3-5 μm) applications. Although HgCdTe based IR imaging dominate the high-performance end of the market, enhancing the signal-to-noise ratio (SNR) performance is still one of the challenges. This is typically dealt with either by improving the quantum efficiency (QE) with the employment of AR surfaces and photon trapping schemes or by decreasing the noise level with a reduction in detector volume. Decreasing either the thickness or the area of the detector, which comes with a performance degradation in QE in return, does the volume reduction. Nevertheless, the reduced QE can be recovered through light concentration with the employment of microlenses in the case of reduced area, which is typically realized with curved lenses presenting curve formation and packaging related issues. These issues can be overcome with the utilization of lithography-compatible metalenses carved into the substrate material. Thus, in this study, a nanohole based array of 40×40 is optimized to be monolithically integrated into CdZnTe (4%) substrate with a placement period of 1.0μm, a depth of around 4.9μm in order to construct a metalens structure with a numerical aperture of 0.63, and operation wavelength of 4.0μm. The nanohole width changes within a range of 0.35μm to 0.83μm in order to provide 2π phase coverage. Single layer of SiO₂ based antireflective surface is introduced to the design in order to enhance the focusing efficiency, which is determined to be around 91%.

Citation Download Citation

Nazmi Yilmaz, Ramazan Cetin, Ahmet Sozak, and Eray Yasan "High efficiency nanohole based immersion metalens for light concentration", Proc. SPIE 11795, Metamaterials, Metadevices, and Metasystems 2021, 117952C (6 August 2021); https://doi.org/10.1117/12.2594114

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