Broadband metalenses monolithically integrated with infrared photodetectors

Tobias Wenger; Alexander Soibel; Richard Muller; Sam Keo; Anita Fisher; Sir Rafol; Daniel Wilson; Sarath Gunapala

doi:10.1117/12.2566262

20 August 2020 Broadband metalenses monolithically integrated with infrared photodetectors

Tobias Wenger, Alexander Soibel, Richard Muller, Sam Keo, Anita Fisher, Sir Rafol, Daniel Wilson, Sarath Gunapala

Proceedings Volume 11460, Metamaterials, Metadevices, and Metasystems 2020; 114601K (2020) https://doi.org/10.1117/12.2566262
Event: SPIE Nanoscience + Engineering, 2020, Online Only

Conference Poster

Abstract

In this work, we utilize metasurface lenses (metalenses) as optical concentrators for photodetectors. In particular, we design and fabricate metalenses for the wavelength range 3.5 -4.5 μm and integrate them with infrared photodetectors. Infrared photodetector technologies, especially in the mid- to long wavelength IR, need to be cooled to achieve optimal performance. Reducing the amount of required cooling will ease their use in space applications where small size, weight and power consumption (SWaP) is of high importance. In this work we address this issue by monolithically integrating metalenses with gallium antimonide (GaSb)-based infrared photodetectors. The metalenses are fabricated on the back side of a GaSb substrate and the detectors are then fabricated on the front side. The metalenses consist of nanopillars and the fabrication is performed by e-beam lithography and ICP plasma etching, leaving metalenses etched into the back side of the GaSb. The nanopillar diameters range from 200 nm to 1.4 μm and the nanopillars all have a height of 2 μm. By back side illuminating the photodetectors (i.e., through the metalenses) we obtain an enhanced optical collection area of the photodetectors and thereby an enhanced detectivity when operated at a specific temperature. Alternatively, this enhanced detectivity can be traded in for an increased operating temperature of the detectors. By being suitable for array-scale fabrication, our work paves the way for future high-operating temperature GaSb-based focal plane arrays.

Citation Download Citation

Tobias Wenger, Alexander Soibel, Richard Muller, Sam Keo, Anita Fisher, Sir Rafol, Daniel Wilson, and Sarath Gunapala "Broadband metalenses monolithically integrated with infrared photodetectors", Proc. SPIE 11460, Metamaterials, Metadevices, and Metasystems 2020, 114601K (20 August 2020); https://doi.org/10.1117/12.2566262

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