Browsing by Author "Xu, Hongxing"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Efficient Second Harmonic Generation in a Hybrid Plasmonic Waveguide by Mode Interactions
    (American Chemical Society, 2019) Shi, Junjun; Li, Yang; Kang, Meng; He, Xiaobo; Halas, Naomi J.; Nordlander, Peter; Zhang, Shunping; Xu, Hongxing; Laboratory for Nanophotonics
    Developing highly efficient nanoscale coherent light sources is essential for advances in technological applications such as integrated photonic circuits, bioimaging, and sensing. An on-chip wavelength convertor based on second harmonic generation (SHG) would be a crucial step toward this goal, but the light-conversion efficiency would be low for small device dimensions. Here we demonstrate strongly enhanced SHG with a high conversion efficiency of 4 × 10–5 W–1 from a hybrid plasmonic waveguide consisting of a CdSe nanowire coupled with a Au film. The strong spatial overlap of the waveguide mode with the nonlinear material and momentum conservation between the incident and reflected modes are the key factors resulting in such high efficiency. The SHG emission angles vary linearly with excitation wavelength, indicating a nonlinear steering of coherent light emission at the subwavelength scale. Our work is promising for the realization of efficient and tunable nonlinear coherent sources and opens new approaches for efficient integrated nonlinear nanophotonic devices.
  • Thumbnail Image
    Item
    Giant photothermoelectric effect in silicon nanoribbon photodetectors
    (Springer Nature, 2020) Dai, Wei; Liu, Weikang; Yang, Jian; Xu, Chao; Alabastri, Alessandro; Liu, Chang; Nordlander, Peter; Guan, Zhiqiang; Xu, Hongxing; Laboratory for Nanophotonics
    The photothermoelectric (PTE) effect enables efficient harvesting of the energy of photogenerated hot carriers and is a promising choice for high-efficiency photoelectric energy conversion and photodetection. Recently, the PTE effect was reported in low-dimensional nanomaterials, suggesting the possibility of optimizing their energy conversion efficiency. Unfortunately, the PTE effect becomes extremely inefficient in low-dimensional nanomaterials, owing to intrinsic disadvantages, such as low optical absorption and immature fabrication methods. In this study, a giant PTE effect was observed in lightly doped p-type silicon nanoribbons caused by photogenerated hot carriers. The open-circuit photovoltage responsivity of the device was 3-4 orders of magnitude higher than those of previously reported PTE devices. The measured photovoltage responses fit very well with the proposed photothermoelectric multiphysics models. This research proposes an application of the PTE effect and a possible method for utilizing hot carriers in semiconductors to significantly improve their photoelectric conversion efficiency.