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Mehmet Mutlu
Absorbing optical antennas: applications in nanophotonics and combustion PhD Thesis
Stanford University, 2018.
@phdthesis{MehmetMutluthesis,
title = {Absorbing optical antennas: applications in nanophotonics and combustion},
author = {Mehmet Mutlu},
url = {http://purl.stanford.edu/nx988rw9001},
year = {2018},
date = {2018-02-01},
school = {Stanford University},
abstract = {The promise of optical antennas is the ability to tame the light to behave in ways not achievable using traditional optical components. For example, our results here demonstrate that a careful engineering of optical antennas allow the strong, even perfect, absorption of light in ultra-thin geometries, i.e., geometries much thinner than the wavelength of light. Enabled by geometry-sensitive antenna resonances, this absorption behavior can also be realized for a broad selection of colors. A detailed theoretical analysis of the observed perfect absorption phenomenon reveals the role of incoherently interacting degenerate electric and magnetic resonances in overcoming the well-known absorption limit for infinitesimally thin films. With another set of experiments, we show that strongly absorbed optical energy in aluminum nanoantennas can be used to heat them efficiently above their melting temperature and stimulate an explosive exothermic oxidation reaction called melt-dispersion mechanism. Importantly, we see that engineering the specific geometry of the constituent particles allows an unprecedented control of aluminum ignition, both spectrally and spatially, through the fine tuning of the optical antenna resonances.},
keywords = {},
pubstate = {published},
tppubtype = {phdthesis}
}
The promise of optical antennas is the ability to tame the light to behave in ways not achievable using traditional optical components. For example, our results here demonstrate that a careful engineering of optical antennas allow the strong, even perfect, absorption of light in ultra-thin geometries, i.e., geometries much thinner than the wavelength of light. Enabled by geometry-sensitive antenna resonances, this absorption behavior can also be realized for a broad selection of colors. A detailed theoretical analysis of the observed perfect absorption phenomenon reveals the role of incoherently interacting degenerate electric and magnetic resonances in overcoming the well-known absorption limit for infinitesimally thin films. With another set of experiments, we show that strongly absorbed optical energy in aluminum nanoantennas can be used to heat them efficiently above their melting temperature and stimulate an explosive exothermic oxidation reaction called melt-dispersion mechanism. Importantly, we see that engineering the specific geometry of the constituent particles allows an unprecedented control of aluminum ignition, both spectrally and spatially, through the fine tuning of the optical antenna resonances.
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.
Mehmet Mutlu; Juhyung Kang; Søren Raza; David T. Schoen; Xiaolin Zheng; Pieter G. Kik; Mark L. Brongersma
Thermoplasmonic Ignition of Metal Nanoparticles Journal Article
In: Nano Lett., vol. 18, no. 3, pp. 1699–1706, 2018.
@article{mutlu2018thermoplasmonic,
title = {Thermoplasmonic Ignition of Metal Nanoparticles},
author = {Mehmet Mutlu and Juhyung Kang and S\oren Raza and David T. Schoen and Xiaolin Zheng and Pieter G. Kik and Mark L. Brongersma},
doi = {10.1021/acs.nanolett.7b04739},
year = {2018},
date = {2018-01-22},
journal = {Nano Lett.},
volume = {18},
number = {3},
pages = {1699\textendash1706},
abstract = {Explosives, propellants, and pyrotechnics are energetic materials that can store and quickly release tremendous amounts of chemical energy. Aluminum (Al) is a particularly important fuel in many applications because of its high energy density, which can be released in a highly exothermic oxidation process. The diffusive oxidation mechanism (DOM) and melt-dispersion mechanism (MDM) explain the ways powders of Al nanoparticles (NPs) can burn, but little is known about the possible use of plasmonic resonances in NPs to manipulate photo-ignition. This is complicated by the inhomogeneous nature of powders and very fast heating and burning rates. Here, we generate Al NPs with well-defined sizes, shapes, and spacings by electron beam lithography and demonstrate that their plasmonic resonances can be exploited to heat and ignite them with a laser. By combining simulations with thermal-emission, electron-, and optical-microscopy studies, we reveal how an improved control over NP ignition can be attained.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Explosives, propellants, and pyrotechnics are energetic materials that can store and quickly release tremendous amounts of chemical energy. Aluminum (Al) is a particularly important fuel in many applications because of its high energy density, which can be released in a highly exothermic oxidation process. The diffusive oxidation mechanism (DOM) and melt-dispersion mechanism (MDM) explain the ways powders of Al nanoparticles (NPs) can burn, but little is known about the possible use of plasmonic resonances in NPs to manipulate photo-ignition. This is complicated by the inhomogeneous nature of powders and very fast heating and burning rates. Here, we generate Al NPs with well-defined sizes, shapes, and spacings by electron beam lithography and demonstrate that their plasmonic resonances can be exploited to heat and ignite them with a laser. By combining simulations with thermal-emission, electron-, and optical-microscopy studies, we reveal how an improved control over NP ignition can be attained.
