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Mohammad Taghinejad; Chenyi Xia; Martin Hrton; Kyu-Tae Lee; Andrew S Kim; Qitong Li; Burak Guzelturk; Radek Kalousek; Fenghao Xu; Wenshan Cai; Aaron M Lindenberg; Mark L Brongersma
Determining hot-carrier transport dynamics from terahertz emission Journal Article
In: Science, vol. 382, iss. 6668, pp. 299-305, 2023.
@article{taghinejad2023determining,
title = {Determining hot-carrier transport dynamics from terahertz emission},
author = {Mohammad Taghinejad and Chenyi Xia and Martin Hrton and Kyu-Tae Lee and Andrew S Kim and Qitong Li and Burak Guzelturk and Radek Kalousek and Fenghao Xu and Wenshan Cai and Aaron M Lindenberg and Mark L Brongersma},
doi = {10.1126/science.adj5612},
year = {2023},
date = {2023-10-20},
urldate = {2023-10-20},
journal = {Science},
volume = {382},
issue = {6668},
pages = {299-305},
abstract = {Understanding the ultrafast excitation and transport dynamics of plasmon-driven hot carriers is critical to the development of optoelectronics, photochemistry, and solar-energy harvesting. However, the ultrashort time and length scales associated with the behavior of these highly out-of-equilibrium carriers have impaired experimental verification of ab initio quantum theories. Here, we present an approach to studying plasmonic hot-carrier dynamics that analyzes the temporal waveform of coherent terahertz bursts radiated by photo-ejected hot carriers from designer nano-antennas with a broken symmetry. For ballistic carriers ejected from gold antennas, we find an ~11-femtosecond timescale composed of the plasmon lifetime and ballistic transport time. Polarization- and phase-sensitive detection of terahertz fields further grant direct access to their ballistic transport trajectory. Our approach opens explorations of ultrafast carrier dynamics in optically excited nanostructures.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Understanding the ultrafast excitation and transport dynamics of plasmon-driven hot carriers is critical to the development of optoelectronics, photochemistry, and solar-energy harvesting. However, the ultrashort time and length scales associated with the behavior of these highly out-of-equilibrium carriers have impaired experimental verification of ab initio quantum theories. Here, we present an approach to studying plasmonic hot-carrier dynamics that analyzes the temporal waveform of coherent terahertz bursts radiated by photo-ejected hot carriers from designer nano-antennas with a broken symmetry. For ballistic carriers ejected from gold antennas, we find an ~11-femtosecond timescale composed of the plasmon lifetime and ballistic transport time. Polarization- and phase-sensitive detection of terahertz fields further grant direct access to their ballistic transport trajectory. Our approach opens explorations of ultrafast carrier dynamics in optically excited nanostructures.
Qitong Li; Jung-Hwan Song; Fenghao Xu; Jorik van de Groep; Jiho Hong; Alwin Daus; Yan Joe Lee; Amalya C Johnson; Eric Pop; Fang Liu; Mark L Brongersma
A Purcell-enabled monolayer semiconductor free-space optical modulator Journal Article
In: Nature Photonics, vol. 17, iss. 10, pp. 897-903, 2023.
@article{li2023purcell,
title = {A Purcell-enabled monolayer semiconductor free-space optical modulator},
author = {Qitong Li and Jung-Hwan Song and Fenghao Xu and Jorik van de Groep and Jiho Hong and Alwin Daus and Yan Joe Lee and Amalya C Johnson and Eric Pop and Fang Liu and Mark L Brongersma},
doi = {10.1038/s41566-023-01250-9},
year = {2023},
date = {2023-07-23},
urldate = {2023-07-23},
journal = {Nature Photonics},
volume = {17},
issue = {10},
pages = {897-903},
abstract = {Dephasing and non-radiative decay processes limit the performance of a wide variety of quantum devices at room temperature. Here we illustrate a general pathway to notably reduce the detrimental impact of these undesired effects through photonic design of the device electrodes. Our design facilitates a large Purcell enhancement that speeds up competing, desired radiative decay while also enabling convenient electrical gating and charge injection functions. We demonstrate the concept with a free-space optical modulator based on an atomically thin semiconductor. By engineering the plasmonic response of a nanopatterned silver gate pad, we successfully enhance the radiative decay rate of excitons in a tungsten disulfide monolayer by one order of magnitude to create record-high modulation efficiencies for this class of materials at room temperature. We experimentally observe a 10% reflectance change as well as 3 dB signal modulation, corresponding to a 20-fold enhancement compared with modulation using a suspended monolayer in vacuum. We also illustrate how dynamic control of light fields can be achieved with designer surface patterns. This research highlights the benefits of applying radiative decay engineering as a powerful tool in creating high-performance devices that complements substantial efforts to improve the quality of materials.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Dephasing and non-radiative decay processes limit the performance of a wide variety of quantum devices at room temperature. Here we illustrate a general pathway to notably reduce the detrimental impact of these undesired effects through photonic design of the device electrodes. Our design facilitates a large Purcell enhancement that speeds up competing, desired radiative decay while also enabling convenient electrical gating and charge injection functions. We demonstrate the concept with a free-space optical modulator based on an atomically thin semiconductor. By engineering the plasmonic response of a nanopatterned silver gate pad, we successfully enhance the radiative decay rate of excitons in a tungsten disulfide monolayer by one order of magnitude to create record-high modulation efficiencies for this class of materials at room temperature. We experimentally observe a 10% reflectance change as well as 3 dB signal modulation, corresponding to a 20-fold enhancement compared with modulation using a suspended monolayer in vacuum. We also illustrate how dynamic control of light fields can be achieved with designer surface patterns. This research highlights the benefits of applying radiative decay engineering as a powerful tool in creating high-performance devices that complements substantial efforts to improve the quality of materials.
Anqi Ji; Jung-Hwan Song; Qitong Li; Fenghao Xu; Ching-Ting Tsai; Richard C Tiberio; Bianxiao Cui; Philippe Lalanne; Pieter G Kik; David AB Miller; Mark L Brongersma
Quantitative phase contrast imaging with a nonlocal angle-selective metasurface Journal Article
In: Nature Communications, vol. 13, iss. 1, pp. 1-7, 2022.
@article{ji2022quantitative,
title = {Quantitative phase contrast imaging with a nonlocal angle-selective metasurface},
author = {Anqi Ji and Jung-Hwan Song and Qitong Li and Fenghao Xu and Ching-Ting Tsai and Richard C Tiberio and Bianxiao Cui and Philippe Lalanne and Pieter G Kik and David AB Miller and Mark L Brongersma},
year = {2022},
date = {2022-12-21},
urldate = {2022-12-21},
journal = {Nature Communications},
volume = {13},
issue = {1},
pages = {1-7},
abstract = {Phase contrast microscopy has played a central role in the development of modern biology, geology, and nanotechnology. It can visualize the structure of translucent objects that remains hidden in regular optical microscopes. The optical layout of a phase contrast microscope is based on a 4 f image processing setup and has essentially remained unchanged since its invention by Zernike in the early 1930s. Here, we propose a conceptually new approach to phase contrast imaging that harnesses the non-local optical response of a guided-mode-resonator metasurface. We highlight its benefits and demonstrate the imaging of various phase objects, including biological cells, polymeric nanostructures, and transparent metasurfaces. Our results showcase that the addition of this non-local metasurface to a conventional microscope enables quantitative phase contrast imaging with a 0.02π phase accuracy. At a high level, this work adds to the growing body of research aimed at the use of metasurfaces for analog optical computing.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Phase contrast microscopy has played a central role in the development of modern biology, geology, and nanotechnology. It can visualize the structure of translucent objects that remains hidden in regular optical microscopes. The optical layout of a phase contrast microscope is based on a 4 f image processing setup and has essentially remained unchanged since its invention by Zernike in the early 1930s. Here, we propose a conceptually new approach to phase contrast imaging that harnesses the non-local optical response of a guided-mode-resonator metasurface. We highlight its benefits and demonstrate the imaging of various phase objects, including biological cells, polymeric nanostructures, and transparent metasurfaces. Our results showcase that the addition of this non-local metasurface to a conventional microscope enables quantitative phase contrast imaging with a 0.02π phase accuracy. At a high level, this work adds to the growing body of research aimed at the use of metasurfaces for analog optical computing.
