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Yifei Wang
Electrically reconfigurable phase-change antennas and metasurfaces PhD Thesis
Stanford University, 2021.
@phdthesis{yifeiwangthesis,
title = {Electrically reconfigurable phase-change antennas and metasurfaces},
author = {Yifei Wang},
url = {https://purl.stanford.edu/gj432wn5811},
year = {2021},
date = {2021-08-28},
address = {Stanford, CA, US},
school = {Stanford University},
abstract = {The success of semiconductor electronics is built on the creation of compact, low-power switching elements that offer routing, logic, and memory functions. The availability of nanoscale optical switches could have a similarly transformative impact on the development of dynamic and programmable metasurfaces, optical neural networks, and quantum information processing. Phase-change materials are uniquely suited to enable the creation of dynamically tunable optical elements and metasurfaces, as they offer high-speed electrical switching between amorphous and crystalline states with notably different optical properties. Their non-volatility also enables metasurface pixels to afford convenient programming of desired functions and a reduced power consumption. The high refractive index of phase change materials has already been harnessed to fashion them into compact optical antennas. Here, we take the next important step, by showing electrically switchable phase-change antennas and metasurfaces that offer strong, reversible, non-volatile, multi-phase switching and spectral tuning of light scattering in the visible and near-infrared spectral ranges. Their successful implementation relies on a careful joint thermal and optical optimization of each optical device that comprises a metal strip that simultaneously serves as a plasmonic resonator and a miniature heating stage. In the dissertation, three functional optical devices are demonstrated with electrical tunability. An optical antenna featuring 30% modulation of the scattered light intensity is first presented and helps us understand our approach of switching phase-change materials. Based on this knowledge, a metasurface is developed, which can afford electrical modulation of the reflectance by more than 4-fold. Lastly, optical antennas are carefully arranged together to build a metasurface that can direct light into different directions and shows promise in individual control of each antenna. The works presented in this dissertation open the opportunity to create a wide range of dynamic random access metasurfaces capable of programmable and active wavefront manipulation},
keywords = {},
pubstate = {published},
tppubtype = {phdthesis}
}
The success of semiconductor electronics is built on the creation of compact, low-power switching elements that offer routing, logic, and memory functions. The availability of nanoscale optical switches could have a similarly transformative impact on the development of dynamic and programmable metasurfaces, optical neural networks, and quantum information processing. Phase-change materials are uniquely suited to enable the creation of dynamically tunable optical elements and metasurfaces, as they offer high-speed electrical switching between amorphous and crystalline states with notably different optical properties. Their non-volatility also enables metasurface pixels to afford convenient programming of desired functions and a reduced power consumption. The high refractive index of phase change materials has already been harnessed to fashion them into compact optical antennas. Here, we take the next important step, by showing electrically switchable phase-change antennas and metasurfaces that offer strong, reversible, non-volatile, multi-phase switching and spectral tuning of light scattering in the visible and near-infrared spectral ranges. Their successful implementation relies on a careful joint thermal and optical optimization of each optical device that comprises a metal strip that simultaneously serves as a plasmonic resonator and a miniature heating stage. In the dissertation, three functional optical devices are demonstrated with electrical tunability. An optical antenna featuring 30% modulation of the scattered light intensity is first presented and helps us understand our approach of switching phase-change materials. Based on this knowledge, a metasurface is developed, which can afford electrical modulation of the reflectance by more than 4-fold. Lastly, optical antennas are carefully arranged together to build a metasurface that can direct light into different directions and shows promise in individual control of each antenna. The works presented in this dissertation open the opportunity to create a wide range of dynamic random access metasurfaces capable of programmable and active wavefront manipulation
Yifei Wang; Patrick Landreman; David Schoen; Kye Okabe; Ann Marshall; Umberto Celano; H.-S. Philip Wong; Junghyun Park; Mark L. Brongersma
Electrical tuning of phase-change antennas and metasurfaces Journal Article
In: Nature Nanotechnology, vol. 16, pp. 667–672, 2021.
@article{wang2021electrical,
title = {Electrical tuning of phase-change antennas and metasurfaces},
author = {Yifei Wang and Patrick Landreman and David Schoen and Kye Okabe and Ann Marshall and Umberto Celano and H.-S. Philip Wong and Junghyun Park and Mark L. Brongersma},
doi = {10.1038/s41565-021-00882-8},
year = {2021},
date = {2021-04-19},
journal = {Nature Nanotechnology},
volume = {16},
pages = {667\textendash672},
abstract = {The success of semiconductor electronics is built on the creation of compact, low-power switching elements that offer routing, logic and memory functions. The availability of nanoscale optical switches could have a similarly transformative impact on the development of dynamic and programmable metasurfaces, optical neural networks and quantum information processing. Phase-change materials are uniquely suited to enable their creation as they offer high-speed electrical switching between amorphous and crystalline states with notably different optical properties. Their high refractive index has already been harnessed to fashion them into compact optical antennas. Here, we take the next important step, by showing electrically-switchable phase-change antennas and metasurfaces that offer strong, reversible, non-volatile, multi-phase switching and spectral tuning of light scattering in the visible and near-infrared spectral ranges. Their successful implementation relies on a careful joint thermal and optical optimization of the antenna elements that comprise a silver strip that simultaneously serves as a plasmonic resonator and a miniature heating stage. Our metasurface affords electrical modulation of the reflectance by more than fourfold at 755 nm.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The success of semiconductor electronics is built on the creation of compact, low-power switching elements that offer routing, logic and memory functions. The availability of nanoscale optical switches could have a similarly transformative impact on the development of dynamic and programmable metasurfaces, optical neural networks and quantum information processing. Phase-change materials are uniquely suited to enable their creation as they offer high-speed electrical switching between amorphous and crystalline states with notably different optical properties. Their high refractive index has already been harnessed to fashion them into compact optical antennas. Here, we take the next important step, by showing electrically-switchable phase-change antennas and metasurfaces that offer strong, reversible, non-volatile, multi-phase switching and spectral tuning of light scattering in the visible and near-infrared spectral ranges. Their successful implementation relies on a careful joint thermal and optical optimization of the antenna elements that comprise a silver strip that simultaneously serves as a plasmonic resonator and a miniature heating stage. Our metasurface affords electrical modulation of the reflectance by more than fourfold at 755 nm.
Guangmin Zhou; Ankun Yang; Yifei Wang; Guoping Gao; Allen Pei; Xiaoyun Yu; Yangying Zhu; Linqi Zong; Bofei Liu; Jinwei Xu; Nian Liu; Jinsong Zhang; Yanxi Li; Lin-Wang Wang; Harold Y. Hwang; Mark L. Brongersma; Steven Chu; Yi Cui
Electrotunable liquid sulfur microdroplets Journal Article
In: Nature Communications, vol. 11, no. 606, 2020.
@article{cuisulfulmicrodroplet,
title = {Electrotunable liquid sulfur microdroplets},
author = {Guangmin Zhou and Ankun Yang and Yifei Wang and Guoping Gao and Allen Pei and Xiaoyun Yu and Yangying Zhu and Linqi Zong and Bofei Liu and Jinwei Xu and Nian Liu and Jinsong Zhang and Yanxi Li and Lin-Wang Wang and Harold Y. Hwang and Mark L. Brongersma and Steven Chu and Yi Cui},
doi = {10.1038/s41467-020-14438-2},
year = {2020},
date = {2020-01-30},
journal = {Nature Communications},
volume = {11},
number = {606},
abstract = {Manipulating liquids with tunable shape and optical functionalities in real time is important for electroactive flow devices and optoelectronic devices, but remains a great challenge. Here, we demonstrate electrotunable liquid sulfur microdroplets in an electrochemical cell. We observe electrowetting and merging of sulfur droplets under different potentiostatic conditions, and successfully control these processes via selective design of sulfiphilic/sulfiphobic substrates. Moreover, we employ the electrowetting phenomena to create a microlens based on the liquid sulfur microdroplets and tune its characteristics in real time through changing the shape of the liquid microdroplets in a fast, repeatable, and controlled manner. These studies demonstrate a powerful in situ optical battery platform for unraveling the complex reaction mechanism of sulfur chemistries and for exploring the rich material properties of the liquid sulfur, which shed light on the applications of liquid sulfur droplets in devices such as microlenses, and potentially other electrotunable and optoelectronic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Manipulating liquids with tunable shape and optical functionalities in real time is important for electroactive flow devices and optoelectronic devices, but remains a great challenge. Here, we demonstrate electrotunable liquid sulfur microdroplets in an electrochemical cell. We observe electrowetting and merging of sulfur droplets under different potentiostatic conditions, and successfully control these processes via selective design of sulfiphilic/sulfiphobic substrates. Moreover, we employ the electrowetting phenomena to create a microlens based on the liquid sulfur microdroplets and tune its characteristics in real time through changing the shape of the liquid microdroplets in a fast, repeatable, and controlled manner. These studies demonstrate a powerful in situ optical battery platform for unraveling the complex reaction mechanism of sulfur chemistries and for exploring the rich material properties of the liquid sulfur, which shed light on the applications of liquid sulfur droplets in devices such as microlenses, and potentially other electrotunable and optoelectronic devices.
Qitong Li; Jorik van de Groep; Yifei Wang; Pieter G. Kik; Mark L. Brongersma
Transparent multispectral photodetectors mimicking the human visual system Journal Article
In: Nature Communications, vol. 10, no. 4982, 2019.
@article{qitong-photodetector,
title = {Transparent multispectral photodetectors mimicking the human visual system},
author = {Qitong Li and Jorik van de Groep and Yifei Wang and Pieter G. Kik and Mark L. Brongersma },
doi = {10.1038/s41467-019-12899-8},
year = {2019},
date = {2019-11-01},
journal = {Nature Communications},
volume = {10},
number = {4982},
abstract = {Compact and lightweight photodetection elements play a critical role in the newly emerging augmented reality, wearable and sensing technologies. In these technologies, devices are preferred to be transparent to form an optical interface between a viewer and the outside world. For this reason, it is of great value to create detection platforms that are imperceptible to the human eye directly onto transparent substrates. Semiconductor nanowires (NWs) make ideal photodetectors as their optical resonances enable parsing of the multi-dimensional information carried by light. Unfortunately, these optical resonances also give rise to strong, undesired light scattering. In this work, we illustrate how a new optical resonance arising from the radiative coupling between arrayed silicon NWs can be harnessed to remove reflections from dielectric interfaces while affording spectro-polarimetric detection. The demonstrated transparent photodetector concept opens up promising platforms for transparent substrates as the base for opto-electronic devices and in situ optical measurement systems.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Compact and lightweight photodetection elements play a critical role in the newly emerging augmented reality, wearable and sensing technologies. In these technologies, devices are preferred to be transparent to form an optical interface between a viewer and the outside world. For this reason, it is of great value to create detection platforms that are imperceptible to the human eye directly onto transparent substrates. Semiconductor nanowires (NWs) make ideal photodetectors as their optical resonances enable parsing of the multi-dimensional information carried by light. Unfortunately, these optical resonances also give rise to strong, undesired light scattering. In this work, we illustrate how a new optical resonance arising from the radiative coupling between arrayed silicon NWs can be harnessed to remove reflections from dielectric interfaces while affording spectro-polarimetric detection. The demonstrated transparent photodetector concept opens up promising platforms for transparent substrates as the base for opto-electronic devices and in situ optical measurement systems.
