All Publications


  • Dynamic Focusing with High-Quality-Factor Metalenses. Nano letters Klopfer, E., Lawrence, M., Barton, D. R., Dixon, J., Dionne, J. A. 2020

    Abstract

    Metasurface lenses provide an ultrathin platform in which to focus light, but weak light-matter interactions limit their dynamic tunability. Here we design submicron-thick, ultrahigh quality factor (high-Q) metalenses that enable dynamic modulation of the focal length and intensity. Using full-field simulations, we show that quality factors exceeding 5000 can be generated by including subtle, periodic perturbations within the constituent Si nanoantennas. Such high-Q resonances enable lens modulation based on the nonlinear Kerr effect, with focal lengths varying from 4 to 6.5 μm and focal intensities decreasing by half as input intensity increases from 0.1 to 1 mW/μm2. We also show how multiple high-Q resonances can be embedded in the lens response through judicious placement of the perturbations. Our high-Q lens design, with quality factors 2 orders of magnitude higher than existing lens designs, provides a foundation for reconfigurable, multiplexed, and hyperspectral metasurface imaging platforms.

    View details for DOI 10.1021/acs.nanolett.0c01359

    View details for PubMedID 32497434

  • Evaluation of a Silicon Sr-90 Betavoltaic Power Source SCIENTIFIC REPORTS Dixon, J., Rajan, A., Bohlemann, S., Coso, D., Upadhyaya, A. D., Rohatgi, A., Chu, S., Majumdar, A., Yee, S. 2016; 6

    Abstract

    Betavoltaic energy converters (i.e., β-batteries) are attractive power sources because of their potential for high energy densities (>200 MWh/kg) and long duration continuous discharge (>1 year). However, conversion efficiencies have been historically low (<3%). High efficiency devices can be achieved by matching β-radiation transport length scales with the device physics length scales. In this work, the efficiency of c-Si devices using high-energy (>1 MeV) electrons emitted from (90)Sr as a power source is investigated. We propose a design for a >10% efficient betavoltaic device, which generates 1 W of power. A Varian Clinac iX is used to simulate the high-energy electrons emitted from (90)Sr, and a high efficiency c-Si photovoltaic cell is used as the converter. The measured conversion efficiency is 16%. This relatively high value is attributed to proper length scale matching and the generation of secondary electrons in c-Si by the primary β-particles.

    View details for DOI 10.1038/srep38182

    View details for Web of Science ID 000388995400001

    View details for PubMedCentralID PMC5131278

  • Sr Betavoltaic Power Source. Scientific reports Dixon, J., Rajan, A., Bohlemann, S., Coso, D., Upadhyaya, A. D., Rohatgi, A., Chu, S., Majumdar, A., Yee, S. 2016; 6: 38182-?

    Abstract

    Betavoltaic energy converters (i.e., β-batteries) are attractive power sources because of their potential for high energy densities (>200 MWh/kg) and long duration continuous discharge (>1 year). However, conversion efficiencies have been historically low (<3%). High efficiency devices can be achieved by matching β-radiation transport length scales with the device physics length scales. In this work, the efficiency of c-Si devices using high-energy (>1 MeV) electrons emitted from (90)Sr as a power source is investigated. We propose a design for a >10% efficient betavoltaic device, which generates 1 W of power. A Varian Clinac iX is used to simulate the high-energy electrons emitted from (90)Sr, and a high efficiency c-Si photovoltaic cell is used as the converter. The measured conversion efficiency is 16%. This relatively high value is attributed to proper length scale matching and the generation of secondary electrons in c-Si by the primary β-particles.

    View details for DOI 10.1038/srep38182

    View details for PubMedID 27905521

    View details for PubMedCentralID PMC5131278

  • Investigation of hydrogen induced fluorescence in C-60 and its potential use in luminescence down shifting applications NANOSCALE Teprovich, J. A., Washington, A. L., Dixon, J., Ward, P. A., Christian, J. H., Peters, B., Zhou, J., Giri, S., Sharp, D. N., Velten, J. A., Compton, R. N., Jena, P., Zidan, R. 2016; 8 (44): 18760-18770

    View details for DOI 10.1039/c6nr05998h

    View details for Web of Science ID 000387858700023