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1. Subwavelength antimonide infrared detector coupled with dielectric resonator antenna

   https://doi.org/10.1117/12.2518807  

   Kazemi, Alireza; Shu, Qingyuan; Dahiya, Vinita; Taghipour, Zahra; Paradis, Pablo; Ball, Christopher; Ronningen, Theodore J.; Zollner, Stefan; Young, Steve M.; Budhu, Jordan; et al (May 2019, Subwavelength Antimonide Infrared Detector Coupled with Dielectric Resonator Antenna)

   Antenna coupled detectors break the intrinsic tradeoff between signal and noise by “collecting over a large area” and “detecting over a small area”. Most antenna coupled detectors in the infrared rely on a metal resonator structure. However, there are losses associated with metallic structures. We have demonstrated a novel long-wave infrared (LWIR) detector that combines a dielectric resonator antenna with an antimonide-based absorber. The detector consists of a 3D, subwavelength InAsSb absorber embedded in a resonant, cylindrical dielectric resonator antenna made of amorphous silicon. This architecture enables the antimonide detection element to shrink to deep subwavelength dimensions, thereby reducing its thermal noise. It is important to note that this concept only applies when (a) the detector noise is limited by bulk noise mechanisms with negligible surface leakage currents and (b) the dominant source of current in the device is due to dark current (such as diffusion) that scales with the volume of the detector. The dielectric resonator enhances the collection of photons with its resonant structure that couples incident radiation to the detector. We will present results on the absorption in structures with and without the dielectric resonator antenna. The signal to noise enhancement in the LWIR photodiodes integrated with the dielectric resonator antenna using radiometric characterization will be discussed. 

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2. Broadband lightweight flat lenses for long-wave infrared imaging

   https://doi.org/10.1073/pnas.1908447116  

   Meem, Monjurul; Banerji, Sourangsu; Majumder, Apratim; Vasquez, Fernando Guevara; Sensale-Rodriguez, Berardi; Menon, Rajesh (October 2019, Proceedings of the National Academy of Sciences)

   We experimentally demonstrate imaging in the long-wave infrared (LWIR) spectral band (8 μm to 12 μm) using a single polymer flat lens based upon multilevel diffractive optics. The device thickness is only 10 μm, and chromatic aberrations are corrected over the entire LWIR band with one surface. Due to the drastic reduction in device thickness, we are able to utilize polymers with absorption in the LWIR, allowing for inexpensive manufacturing via imprint lithography. The weight of our lens is less than 100 times those of comparable refractive lenses. We fabricated and characterized 2 different flat lenses. Even with about 25% absorption losses, experiments show that our flat polymer lenses obtain good imaging with field of view of 35° and angular resolution less than 0.013°. The flat lenses were characterized with 2 different commercial LWIR image sensors. Finally, we show that, by using lossless, higher-refractive-index materials like silicon, focusing efficiencies in excess of 70% can be achieved over the entire LWIR band. Our results firmly establish the potential for lightweight, ultrathin, broadband lenses for high-quality imaging in the LWIR band. 

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3. Ultra-thin plasmonic detectors

   https://doi.org/10.1364/OPTICA.438039  

   Nordin, Leland; Petluru, Priyanka; Kamboj, Abhilasha; Muhowski, Aaron_J; Wasserman, Daniel (December 2021, Optica)

   Plasmonic materials, and their ability to enable strong concentration of optical fields, have offered a tantalizing foundation for the demonstration of sub-diffraction-limit photonic devices. However, practical and scalable plasmonic optoelectronics for real world applications remain elusive. In this work, we present an infrared photodetector leveraging a device architecture consisting of a “designer” epitaxial plasmonic metal integrated with a quantum-engineered detector structure, all in a mature III-V semiconductor material system. Incident light is coupled into surface plasmon-polariton modes at the detector/designer metal interface, and the strong confinement of these modes allows for a sub-diffractive ( $\sim <\#comment/>{\mathrm{\lambda <\#comment/>}}_0/33$) detector absorber layer thickness, effectively decoupling the detector’s absorption efficiency and dark current. We demonstrate high-performance detectors operating at non-cryogenic temperatures ( $T=195\mathrm{K}$), without sacrificing external quantum efficiency, and superior to well-established and commercially available detectors. This work provides a practical and scalable plasmonic optoelectronic device architecture with real world mid-infrared applications. 

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4. High operating temperature plasmonic infrared detectors

   https://doi.org/10.1063/5.0077456  

   Nordin, L.; Muhowski, A. J.; Wasserman, D. (March 2022, Applied Physics Letters)

   III–V semiconductor type-II superlattices (T2SLs) are a promising material system with the potential to significantly reduce the dark current of, and thus realize high-performance in, infrared photodetectors at elevated temperatures. However, T2SLs have struggled to meet the performance metrics set by the long-standing infrared detector material of choice, HgCdTe. Recently, epitaxial plasmonic detector architectures have demonstrated T2SL detector performance comparable to HgCdTe in the 77–195 K temperature range. Here, we demonstrate a high operating temperature plasmonic T2SL detector architecture with high-performance operation at temperatures accessible with two-stage thermoelectric coolers. Specifically, we demonstrate long-wave infrared plasmonic detectors operating at temperatures as high as 230 K while maintaining dark currents below the “Rule 07” heuristic. At a detector operating temperature of 230 K, we realize 22.8% external quantum efficiency in a detector absorber only 372 nm thick ([Formula: see text]) with a peak specific detectivity of 2.29 × 10⁹cm Hz^1∕2W⁻¹at 9.6  μm, well above commercial detectors at the same operating temperature. 

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5. Plasma-assisted light bullets and wavelength scaling of laser filamentation in the long-wavelength infrared

   Grynko, Rostislav; Nagar, Garima; Shim, Bonggu (October 2018, APS Division of Plasma Physics Meeting 2018)

   We model laser filamentation in ZnSe in the mid-infrared (Mid-IR, wavelengths λ = 4 and 6 μm) and the long-wavelength infrared (LWIR, λ = 8 and 10 μm) using carrier-resolved unidirectional pulse propagation equations (UPPE). We predict an unprecedented propagation regime at λ = 8 μm that supports light bullets, which are spatio-temporally non-spreading electromagnetic pulses. Furthermore, in contrast to the previous report in air in the mid-IR, we predict that LWIR light bullets in solids critically rely on plasma-mediated dispersion, which dynamically evolves during multiphoton and tunneling ionization as peak plasma densities reach ρ 6.6 ×10^18 cm-3 . Finally, the plasma-assisted light bullets propagate with sub-cycle pulse durations and peak intensities I = 1.1 ×10^12 W /cm^2 , making them useful for high-harmonic generation and attosecond pulse generation. 

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