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Application of plasmonic subwavelength structuring to enhance infrared detection

Proceedings of SPIE - The International Society for Optical Engineering

Davids, Paul D.; Kim, Jin K.; Leonhardt, Darin L.; Beechem, Thomas E.; Howell, Stephen W.; Ohta, Taisuke O.; Wendt, J.R.; Montoya, John A.

Nanoantennas are an enabling technology for visible to terahertz components and may be used with a variety of detector materials. We have integrated subwavelength patterned metal nanoantennas with various detector materials for infrared detection: midwave infrared indium gallium arsenide antimonide detectors, longwave infrared graphene detectors, and shortwave infrared germanium detectors. Nanoantennas offer a means to make infrared detectors much thinner, thus lowering the dark current and improving performance. The nanoantenna converts incoming plane waves to more tightly bound and concentrated surface waves. The active material only needs to extend as far as these bound fields. In the case of graphene detectors, which are only one or two atomic layers thick, such field concentration is a necessity for usable device performance, as single pass absorption is insufficient. The nanoantenna is thus the enabling component of these thin devices. However nanoantenna integration and fabrication vary considerably across these platforms as do the considerations taken into account during design. Here we discuss the motivation for these devices and show examples for the three material systems. Characterization results are included for the midwave infrared detector. © 2014 SPIE.

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Nanoantenna-enabled midwave infrared focal plane arrays

Proceedings of SPIE - The International Society for Optical Engineering

Peters, D.W.; Reinke, Charles M.; Davids, Paul D.; Klem, John F.; Leonhardt, Darin L.; Wendt, J.R.; Kim, Jin K.; Samora, S.

We demonstrate the effects of integrating a nanoantenna to a midwave infrared (MWIR) focal plane array (FPA). We model an antenna-coupled photodetector with a nanoantenna fabricated in close proximity to the active material of a photodetector. This proximity allows us to take advantage of the concentrated plasmonic fields of the nanoantenna. The role of the nanoantenna is to convert free-space plane waves into surface plasmons bound to a patterned metal surface. These plasmonic fields are concentrated in a small volume near the metal surface. Field concentration allows for a thinner layer of absorbing material to be used in the photodetector design and promises improvements in cutoff wavelength and dark current (higher operating temperature). While the nanoantenna concept may be applied to any active photodetector material, we chose to integrate the nanoantenna with an InAsSb photodiode. The geometry of the nanoantenna-coupled detector is optimized to give maximal carrier generation in the active region of the photodiode, and fabrication processes must be altered to accommodate the nanoantenna structure. The intensity profiles and the carrier generation rates in the photodetector active layers are determined by finite element method simulations, and iteration between optical nanoantenna simulation and detector modeling is used to optimize the device structure. © 2012 SPIE.

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Channeling light into quantum-scale gaps

Physical Review B - Condensed Matter and Materials Physics

Kekatpure, Rohan D.; Davids, Paul D.

We develop a discrete plasmonic mode-matching technique to investigate the ultimate limits to plasmonic light concentration down to the length scales required for observation of quantum-mechanical phenomena, including plasmon-assisted electron tunneling. Our mode-matching calculations, verified by direct numerical solution of Maxwell's equations, indicate achievable coupling efficiencies of >20% into symmetric bound gap plasmon modes in sub-10-nm gaps. For a given operating wavelength and a choice of material parameters, we demonstrate the existence of a specific width that maximizes enhancement of the electromagnetic field coupled into the gap. More generally, our calculations establish an intuitive and a computationally efficient framework for determining coupling efficiencies in and out of quantum-scale waveguides. © 2011 American Physical Society.

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Plasmonic integrated optics : going the last few microns

Davids, Paul D.

Plasmonic integrated optics is an attempt to bridge the length scale gap between optics and nanometer scale electronic devices. Here we present a hybrid optical interconnect scheme which utilizes low loss dielectric waveguides for global interconnection and plasmonic structures for tightly confining light for local routing and mode manipulation.

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Results 76–100 of 102
Results 76–100 of 102