Professor in Electrical Engineering at Korea University
Recent news
Publications
Jiho Hong; Jorik van de Groep; Nayeun Lee; Soo Jin Kim; Philippe Lalanne; Pieter G. Kik; Mark L. Brongersma
Nonlocal metasurface for circularly polarized light detection Journal Article
In: Optica, vol. 10, no. 1, pp. 134-141, 2023.
@article{Hong:23,
title = {Nonlocal metasurface for circularly polarized light detection},
author = {Jiho Hong and Jorik van de Groep and Nayeun Lee and Soo Jin Kim and Philippe Lalanne and Pieter G. Kik and Mark L. Brongersma},
doi = {10.1364/OPTICA.468252},
year = {2023},
date = {2023-01-20},
journal = {Optica},
volume = {10},
number = {1},
pages = {134-141},
abstract = {Modern-day sensing and imaging applications increasingly rely on accurate measurements of the primary physical quantities associated with light waves: intensity, wavelength, directionality, and polarization. These are conventionally performed with a series of bulky optical elements, but recently, it has been recognized that optical resonances in nanostructures can be engineered to achieve selective photodetection of light waves with a specific set of predetermined properties. Here, we theoretically illustrate how a thin silicon layer can be patterned into a dislocated nanowire-array that affords detection of circularly polarized light with an efficiency that reaches the theoretical limit for circular dichroism of a planar detector in a symmetric external environment. The presence of a periodic arrangement of dislocations is essential in achieving such unparalleled performance as they enable selective excitation of nonlocal, guided-mode resonances for one handedness of light. We also experimentally demonstrate compact, high-performance chiral photodetectors created from these dislocated nanowire-arrays. This work highlights the critical role defects can play in enabling new nanophotonic functions and devices.},
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pubstate = {published},
tppubtype = {article}
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Modern-day sensing and imaging applications increasingly rely on accurate measurements of the primary physical quantities associated with light waves: intensity, wavelength, directionality, and polarization. These are conventionally performed with a series of bulky optical elements, but recently, it has been recognized that optical resonances in nanostructures can be engineered to achieve selective photodetection of light waves with a specific set of predetermined properties. Here, we theoretically illustrate how a thin silicon layer can be patterned into a dislocated nanowire-array that affords detection of circularly polarized light with an efficiency that reaches the theoretical limit for circular dichroism of a planar detector in a symmetric external environment. The presence of a periodic arrangement of dislocations is essential in achieving such unparalleled performance as they enable selective excitation of nonlocal, guided-mode resonances for one handedness of light. We also experimentally demonstrate compact, high-performance chiral photodetectors created from these dislocated nanowire-arrays. This work highlights the critical role defects can play in enabling new nanophotonic functions and devices.
Jung-Hwan Song; Jorik van de Groep; Soo Jin Kim; Mark L. Brongersma
Non-local metasurfaces for spectrally decoupled wavefront manipulation and eye tracking Journal Article
In: Nature Nanotechnology, vol. 16, no. 11, pp. 1224-1230, 2021.
@article{song2021non,
title = {Non-local metasurfaces for spectrally decoupled wavefront manipulation and eye tracking},
author = {Jung-Hwan Song and Jorik van de Groep and Soo Jin Kim and Mark L. Brongersma},
doi = {10.1038/s41565-021-00967-4},
year = {2021},
date = {2021-09-30},
journal = {Nature Nanotechnology},
volume = {16},
number = {11},
pages = {1224-1230},
keywords = {},
pubstate = {published},
tppubtype = {article}
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Junghyun Park; Soo Jin Kim; Patrick Landreman; Mark L. Brongersma
An Over‐Coupled Phase‐Change Metasurface for Efficient Reflection Phase Modulation Journal Article
In: Advanced Optical Materials, vol. 8, no. 2000745, 2020.
@article{parkover,
title = {An Over‐Coupled Phase‐Change Metasurface for Efficient Reflection Phase Modulation},
author = {Junghyun Park and Soo Jin Kim and Patrick Landreman and Mark L. Brongersma},
doi = {10.1002/adom.202000745},
year = {2020},
date = {2020-08-26},
journal = {Advanced Optical Materials},
volume = {8},
number = {2000745},
abstract = {An over‐coupled, thermally tunable metasurface reflect‐array that employs the phase change material Ge2Sb2Te5 (GST) is presented. The metasurface is constructed from gap plasmon cavities in which GST is incorporated as the active switching medium. Upon annealing at 200 °C for 10 min, the GST layer undergoes a transition from the amorphous state to the crystalline state, and this leads to a unity‐order increase of the refractive index. This is accompanied by a spectral shift of 1.6 µm in the resonance wavelength of the plasmonic cavities, larger than their resonance linewidth of 1.2 µm. It is shown that the low material absorption of the GST layer enables operation of the metasurface in the desirable over‐coupled regime. The numerical analysis indicates that this facilitates large changes in the reflection phase (up to 270°) and amplitude. The work opens the possibility of creating efficient reconfigurable metasurfaces for various applications, including holographic displays and image sensors.},
keywords = {},
pubstate = {published},
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An over‐coupled, thermally tunable metasurface reflect‐array that employs the phase change material Ge2Sb2Te5 (GST) is presented. The metasurface is constructed from gap plasmon cavities in which GST is incorporated as the active switching medium. Upon annealing at 200 °C for 10 min, the GST layer undergoes a transition from the amorphous state to the crystalline state, and this leads to a unity‐order increase of the refractive index. This is accompanied by a spectral shift of 1.6 µm in the resonance wavelength of the plasmonic cavities, larger than their resonance linewidth of 1.2 µm. It is shown that the low material absorption of the GST layer enables operation of the metasurface in the desirable over‐coupled regime. The numerical analysis indicates that this facilitates large changes in the reflection phase (up to 270°) and amplitude. The work opens the possibility of creating efficient reconfigurable metasurfaces for various applications, including holographic displays and image sensors.
Amr M. Shaltout; Konstantinos G. Lagoudakis; Jorik van de Groep; Soo Jin Kim; Jelena Vučković; Vladimir M. Shalaev; Mark L. Brongersma
Spatiotemporal light control with frequency-gradient metasurfaces Journal Article
In: Science, vol. 365, no. 6451, pp. 374-377, 2019.
@article{shaltout2019spatiotemporalb,
title = {Spatiotemporal light control with frequency-gradient metasurfaces},
author = {Amr M. Shaltout and Konstantinos G. Lagoudakis and Jorik van de Groep and Soo Jin Kim and Jelena Vu\v{c}kovi\'{c} and Vladimir M. Shalaev and Mark L. Brongersma},
doi = {10.1126/science.aax2357},
year = {2019},
date = {2019-07-26},
journal = {Science},
volume = {365},
number = {6451},
pages = {374-377},
abstract = {The capability of on-chip wavefront modulation has the potential to revolutionize many optical device technologies. However, the realization of power-efficient phase-gradient metasurfaces that offer full-phase modulation (0 to 2π) and high operation speeds remains elusive. We present an approach to continuously steer light that is based on creating a virtual frequency-gradient metasurface by combining a passive metasurface with an advanced frequency-comb source. Spatiotemporal redirection of light naturally occurs as optical phase-fronts reorient at a speed controlled by the frequency gradient across the virtual metasurface. An experimental realization of laser beam steering with a continuously changing steering angle is demonstrated with a single metasurface over an angle of 25° in just 8 picoseconds. This work can support integrated-on-chip solutions for spatiotemporal optical control, directly affecting emerging applications such as solid-state light detection and ranging (LIDAR), three-dimensional imaging, and augmented or virtual systems.},
keywords = {},
pubstate = {published},
tppubtype = {article}
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The capability of on-chip wavefront modulation has the potential to revolutionize many optical device technologies. However, the realization of power-efficient phase-gradient metasurfaces that offer full-phase modulation (0 to 2π) and high operation speeds remains elusive. We present an approach to continuously steer light that is based on creating a virtual frequency-gradient metasurface by combining a passive metasurface with an advanced frequency-comb source. Spatiotemporal redirection of light naturally occurs as optical phase-fronts reorient at a speed controlled by the frequency gradient across the virtual metasurface. An experimental realization of laser beam steering with a continuously changing steering angle is demonstrated with a single metasurface over an angle of 25° in just 8 picoseconds. This work can support integrated-on-chip solutions for spatiotemporal optical control, directly affecting emerging applications such as solid-state light detection and ranging (LIDAR), three-dimensional imaging, and augmented or virtual systems.
Soo Jin Kim; Ju-Hyung Kang; Mehmet Mutlu; Joonsuk Park; Woosung Park; Kenneth E. Goodson; Robert Sinclair; Shanhui Fan; Pieter G. Kik; Mark L. Brongersma
Anti-Hermitian photodetector facilitating efficient subwavelength photon sorting Journal Article
In: Nature Communications, vol. 9, no. 316, 2018.
@article{brongersma2018anti,
title = {Anti-Hermitian photodetector facilitating efficient subwavelength photon sorting},
author = {Soo Jin Kim and Ju-Hyung Kang and Mehmet Mutlu and Joonsuk Park and Woosung Park and Kenneth E. Goodson and Robert Sinclair and Shanhui Fan and Pieter G. Kik and Mark L. Brongersma},
doi = {10.1038/s41467-017-02496-y},
year = {2018},
date = {2018-01-22},
journal = {Nature Communications},
volume = {9},
number = {316},
abstract = {The ability to split an incident light beam into separate wavelength bands is central to a diverse set of optical applications, including imaging, biosensing, communication, photocatalysis, and photovoltaics. Entirely new opportunities are currently emerging with the recently demonstrated possibility to spectrally split light at a subwavelength scale with optical antennas. Unfortunately, such small structures offer limited spectral control and are hard to exploit in optoelectronic devices. Here, we overcome both challenges and demonstrate how within a single-layer metafilm one can laterally sort photons of different wavelengths below the free-space diffraction limit and extract a useful photocurrent. This chipscale demonstration of anti-Hermitian coupling between resonant photodetector elements also facilitates near-unity photon-sorting efficiencies, near-unity absorption, and a narrow spectral response (∼ 30 nm) for the different wavelength channels. This work opens up entirely new design paradigms for image sensors and energy harvesting systems in which the active elements both sort and detect photons.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The ability to split an incident light beam into separate wavelength bands is central to a diverse set of optical applications, including imaging, biosensing, communication, photocatalysis, and photovoltaics. Entirely new opportunities are currently emerging with the recently demonstrated possibility to spectrally split light at a subwavelength scale with optical antennas. Unfortunately, such small structures offer limited spectral control and are hard to exploit in optoelectronic devices. Here, we overcome both challenges and demonstrate how within a single-layer metafilm one can laterally sort photons of different wavelengths below the free-space diffraction limit and extract a useful photocurrent. This chipscale demonstration of anti-Hermitian coupling between resonant photodetector elements also facilitates near-unity photon-sorting efficiencies, near-unity absorption, and a narrow spectral response (∼ 30 nm) for the different wavelength channels. This work opens up entirely new design paradigms for image sensors and energy harvesting systems in which the active elements both sort and detect photons.
Xiaoge Liu; Ju-Hyung Kang; Hongtao Yuan; Junghyun Park; Soo Jin Kim; Yi Cui; Harold Y. Hwang; Mark L. Brongersma
Electrical tuning of a quantum plasmonic resonance Journal Article
In: Nature Nanotechnology, vol. 12, pp. 866–870, 2017.
@article{liu2017electrical,
title = {Electrical tuning of a quantum plasmonic resonance},
author = {Xiaoge Liu and Ju-Hyung Kang and Hongtao Yuan and Junghyun Park and Soo Jin Kim and Yi Cui and Harold Y. Hwang and Mark L. Brongersma},
doi = {10.1038/nnano.2017.103},
year = {2017},
date = {2017-06-12},
journal = {Nature Nanotechnology},
volume = {12},
pages = {866\textendash870},
abstract = {Surface plasmon (SP) excitations in metals facilitate confinement of light into deep-subwavelength volumes and can induce strong light\textendashmatter interaction. Generally, the SP resonances supported by noble metal nanostructures are explained well by classical models, at least until the nanostructure size is decreased to a few nanometres, approaching the Fermi wavelength λF of the electrons. Although there is a long history of reports on quantum size effects in the plasmonic response of nanometre-sized metal particles, systematic experimental studies have been hindered by inhomogeneous broadening in ensemble measurements, as well as imperfect control over size, shape, faceting, surface reconstructions, contamination, charging effects and surface roughness in single-particle measurements. In particular, observation of the quantum size effect in metallic films and its tuning with thickness has been challenging as they only confine carriers in one direction. Here, we show active tuning of quantum size effects in SP resonances supported by a 20-nm-thick metallic film of indium tin oxide (ITO), a plasmonic material serving as a low-carrier-density Drude metal. An ionic liquid (IL) is used to electrically gate and partially deplete the ITO layer. The experiment shows a controllable and reversible blue-shift in the SP resonance above a critical voltage. A quantum-mechanical model including the quantum size effect reproduces the experimental results, whereas a classical model only predicts a red shift.},
keywords = {},
pubstate = {published},
tppubtype = {article}
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Surface plasmon (SP) excitations in metals facilitate confinement of light into deep-subwavelength volumes and can induce strong light–matter interaction. Generally, the SP resonances supported by noble metal nanostructures are explained well by classical models, at least until the nanostructure size is decreased to a few nanometres, approaching the Fermi wavelength λF of the electrons. Although there is a long history of reports on quantum size effects in the plasmonic response of nanometre-sized metal particles, systematic experimental studies have been hindered by inhomogeneous broadening in ensemble measurements, as well as imperfect control over size, shape, faceting, surface reconstructions, contamination, charging effects and surface roughness in single-particle measurements. In particular, observation of the quantum size effect in metallic films and its tuning with thickness has been challenging as they only confine carriers in one direction. Here, we show active tuning of quantum size effects in SP resonances supported by a 20-nm-thick metallic film of indium tin oxide (ITO), a plasmonic material serving as a low-carrier-density Drude metal. An ionic liquid (IL) is used to electrically gate and partially deplete the ITO layer. The experiment shows a controllable and reversible blue-shift in the SP resonance above a critical voltage. A quantum-mechanical model including the quantum size effect reproduces the experimental results, whereas a classical model only predicts a red shift.
