Dr. Bryan T. Spann Profile

Dr. Bryan T. Spann

Staff Research Scientist at Lockheed Martin

Publications (7)

Proceedings Article | 14 May 2019 Presentation

Actively modulated surface phonon polariton resonances within the long‑wave and far-infrared (Conference Presentation)

Chase Ellis, Adam Dunkelberger, Virginia Wheeler, Daniel Ratchford, Dmitry Chigrin, Marc Currie, Mijin Kim, Chul Soo Kim, Alexander Giles, Bryan Spann, Igor Vurgaftman, Jeffrey Owrutsky, Joshua Caldwell, Joseph Tischler

Proceedings Volume 10983, 1098312 (2019) https://doi.org/10.1117/12.2519912

KEYWORDS: Modulation, Phonons, Polaritons, Silicon carbide, Plasmonics, Dielectrics, Reflectance spectroscopy, Nanostructuring, Resonators, Nanolithography

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The high optical losses of metal-based plasmonic materials have driven an extensive search for alternative lower-loss materials that can support plasmonic-like effects, such as sub-diffraction confinement of optical fields. One such alternative employs phonon-mediated collective-charge oscillations (surface phonon polaritons, SPhPs) that can be optically excited in nanostructured polar dielectric materials. Similar to plasmonics, tailoring the geometry of polar-dielectric resonators results in resonances that can be spectrally tuned throughout the spectral range between the LO and TO phonons. However, generally, the spectral position and amplitude of these resonances remain fixed after sample fabrication. In this presentation, we discuss recent advancements made by our group in achieving actively tunable localized SPhP resonances in the long-wave- and far-infrared spectral regimes. In particular, we focus on three experiments that demonstrate active modulation of resonances. The first and second experiments focus on tuning the spectral position of localized SPhP resonances in cylindrical nanopillars that are etched into indium phosphide and silicon carbide substrates. In both of these cases we are able to induce resonance shifts as large as 15 cm-1 by optically injecting free-carriers into the pillars. The optical injection introduces a reversible, free-carrier perturbation to the dielectric permittivity that results in a spectral shift of the resonances. While the effects investigated for both the InP and SiC systems are similar, each material allows us to explore a different aspect of the phenomena. For InP we investigate the effects in the far-infrared (303-344 cm-1) with steady-state carrier photoinjection, while for SiC we investigate the dynamics of frequency modulated resonances in the long-wave infrared (797-972 cm-1) via transient reflection spectroscopy. Lastly, in the third experiment we demonstrate the ability to modulate the amplitude of resonances by coating SiC nanopillars with vanadium dioxide, a well-known phase change material that undergoes a metal-to-insulator transition near a temperature of 70 C. As such, we show that by exploiting this phase change we are able to modulate the reflectance and thermal emission of nanopillar arrays. The results described in this work may open the door to tunable, narrow-band thermal sources that operate in the long-wave to far-infrared spectral regimes.

Proceedings Article | 17 September 2018 Presentation

Localized phonon-polariton modes in periodic GaN nanowire arrays grown by selective area epitaxy (Conference Presentation)

Bryan Spann, Joshua Nolen, Matt Brubaker, Thomas Folland, Chase Ellis, Joseph Tischler, Todd Harvey, Joshua Caldwell, Kris Bertness

Proceedings Volume 10719, 107191G (2018) https://doi.org/10.1117/12.2322885

KEYWORDS: Gallium nitride, Nanowires, Epitaxy, Raman spectroscopy, Semiconductors, Nanostructures, Reflectivity, Electromagnetism, Photonics, Mid-IR

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Proceedings Article | 11 September 2018 Paper

Core-shell p-i-n GaN nanowire LEDs by N-polar selective area growth

Matt Brubaker, Kristen Genter, Joel Weber, Bryan Spann, Alexana Roshko, Paul Blanchard, Todd Harvey, Kris Bertness

Proceedings Volume 10725, 1072502 (2018) https://doi.org/10.1117/12.2322832

KEYWORDS: Light emitting diodes, Gallium nitride, Nanowires, Electroluminescence, Silicon, Measurement devices, Luminescence, Aluminum nitride

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Proceedings Article | 9 November 2016 Presentation

Relaxation dynamics and coherent energy exchange in coupled vibration-cavity polaritons (Conference Presentation)

Blake Simpkins, Kenan Fears, Walter Dressick, Adam Dunkelberger, Bryan Spann, Jeffrey Owrutsky

Proceedings Volume 9918, 991811 (2016) https://doi.org/10.1117/12.2237043

KEYWORDS: Polaritons, Optical resonators, Ultrafast phenomena, Ultrafast measurement systems, Absorption, Infrared radiation, Standards development, Polymethylmethacrylate, Metamaterials, Current controlled current source

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Proceedings Article | 5 October 2015 Presentation

Quantifying energy transfer in semiconductor nanocrystals using coherent phonon manipulation and ultrafast spectroscopy (Presentation Recording)

Bryan Spann, Xianfan Xu

Proceedings Volume 9562, 956206 (2015) https://doi.org/10.1117/12.2186831

KEYWORDS: Nanocrystals, Phonons, Semiconductors, Ultrafast laser spectroscopy, Energy transfer, Solar energy, Photovoltaics, Solar cells, Absorption spectroscopy, Pulse shaping

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Proceedings Article | 5 October 2015 Presentation

Coherent coupling between a molecular vibration and Fabry-Perot optical cavity to give hybridized states in the strong coupling limit (Presentation Recording)

James Long, Jeff Owrutsky, Kenan Fears, Walter Dressick, Adam Dunkelberger, Ryan Compton, Bryan Spann, Blake Simpkins

Proceedings Volume 9546, 954617 (2015) https://doi.org/10.1117/12.2187040

KEYWORDS: Fabry–Perot interferometers, Optical resonators, Infrared radiation, Visible radiation, Ultrafast phenomena, Absorption, Liquids, Video, Current controlled current source

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Proceedings Article | 5 October 2015 Presentation

Understanding carrier injection effects upon the Reststrahlen band of SiC using transient infrared spectroscopy (Presentation Recording)

Bryan Spann, Ryan Compton, Adam Dunkelberger, James Long, Paul Klein, Daniel Ratchford, Josh Caldwell, Jeff Owrutsky

Proceedings Volume 9546, 95460M (2015) https://doi.org/10.1117/12.2187111

KEYWORDS: Silicon carbide, Infrared spectroscopy, Phonons, Photons, Carbon dioxide lasers, Reflectivity, Metamaterials, Plasmonics, Polaritons, Infrared imaging

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Showing 5 of 7 publications

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