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Patrik Rohner

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Papers by Patrik Rohner

Colloidal-quantum-dot spasers and plasmonic amplifiers

arXiv (Cornell University), Nov 29, 2016

Colloidal quantum dots 1 are robust, efficient, and tunable emitters now used in lighting 2-6 , d... more Colloidal quantum dots 1 are robust, efficient, and tunable emitters now used in lighting 2-6 , displays 7 , and lasers 8-11. Consequently, when the spaser 12-a laser-like source of surface plasmons-was first proposed 13 , quantum dots were specified as the ideal plasmonic gain medium. Subsequent spaser designs 14-17 , however, have required a single material to simultaneously provide gain and define the plasmonic cavity, an approach ill-suited to quantum dots and other colloidal nanomaterials. Here we develop a more open architecture that decouples the gain medium from the cavity, leading to a versatile class of quantum-dot-based spasers that allow controlled generation, extraction, and manipulation of plasmons. We first create high-qualityfactor, aberration-corrected, Ag plasmonic cavities. We then incorporate quantum dots via electrohydrodynamic printing 18,19 or drop-casting. Photoexcitation under ambient conditions generates monochromatic plasmons above threshold. This signal is extracted, directed through an integrated amplifier, and focused at a nearby nanoscale tip, generating intense electromagnetic fields. This spaser platform, deployable at different wavelengths, size scales, and geometries, can enable more complex on-chip plasmonic devices.

Acoustic Metal Particle Focusing in a Round Glass Capillary

arXiv (Cornell University), May 24, 2021

Two-dimensional metal particle focusing is an essential task for various fabrication processes. W... more Two-dimensional metal particle focusing is an essential task for various fabrication processes. While acoustofluidic devices can manipulate particles in two dimensions, the production of these devices often demands a cleanroom environment. Therefore, acoustically excited glass capillaries present a cheap alternative to labour-intensive cleanroom production. Here, we present 2D metal micro-particle focusing in a round glass capillary using bulk acoustic waves. Excitation of the piezoelectric transducer at specific frequencies leads to mode shapes in the round capillary, concentrating particles towards the capillary centre. We experimentally investigate the particle linewidth for different particle materials and concentrations. We demonstrate the focus of copper particles with ∼ 1 µm in diameter down to a line of width 60.8 ± 7.0 µm and height 45.2 ± 9.3 µm, corresponding to a local concentration of 4.5 % v/v, which is 90 times higher than the concentration of the initial solution. Through numerical analysis, we could obtain further insights into the particle manipulation mechanism inside the capillary and predict the particle trajectories. We found that a transition of the acoustic streaming pattern enables us to manipulate particles close to the critical particle radius. Finally, we used our method to eject copper particles through a tapered round capillary with an opening of 25 µm in diameter, which would not be possible without particle focusing. Our novel setup can be utilized for various applications, that otherwise might suffer from abrasion, clogging and limited resolution.

Acoustic Metal Particle Focusing in a Round Glass Capillary

arXiv (Cornell University), May 24, 2021

Two-dimensional metal particle focusing is an essential task for various fabrication processes. W... more Two-dimensional metal particle focusing is an essential task for various fabrication processes. While acoustofluidic devices can manipulate particles in two dimensions, the production of these devices often demands a cleanroom environment. Therefore, acoustically excited glass capillaries present a cheap alternative to labour-intensive cleanroom production. Here, we present 2D metal micro-particle focusing in a round glass capillary using bulk acoustic waves. Excitation of the piezoelectric transducer at specific frequencies leads to mode shapes in the round capillary, concentrating particles towards the capillary centre. We experimentally investigate the particle linewidth for different particle materials and concentrations. We demonstrate the focus of copper particles with ∼ 1 µm in diameter down to a line of width 60.8 ± 7.0 µm and height 45.2 ± 9.3 µm, corresponding to a local concentration of 4.5 % v/v, which is 90 times higher than the concentration of the initial solution. Through numerical analysis, we could obtain further insights into the particle manipulation mechanism inside the capillary and predict the particle trajectories. We found that a transition of the acoustic streaming pattern enables us to manipulate particles close to the critical particle radius. Finally, we used our method to eject copper particles through a tapered round capillary with an opening of 25 µm in diameter, which would not be possible without particle focusing. Our novel setup can be utilized for various applications, that otherwise might suffer from abrasion, clogging and limited resolution.

Focusing of Micrometer-Sized Metal Particles Enabled by Reduced Acoustic Streaming via Acoustic Forces in a Round Glass Capillary

Physical Review Applied, 2022

This page was generated automatically upon download from the ETH Zurich Research Collection. For ... more

Deterministic Nanoprinting of Single Fluorescent Molecules

We report direct non-contact electrohydrodynamic nanodrip printing of a countable number of photo... more

Zusammenfassung Numerische Mathematik

Probing Electromagnetic Modes at Optical Frequencies with Eu3+-Doped Nanocrystals

Proceedings of the nanoGe Fall Meeting 2018

Colloidal Quantum-Dot Spasers and Plasmonic Amplifiers

Advanced Photonics 2017 (IPR, NOMA, Sensors, Networks, SPPCom, PS), 2017

Colloidal quantum dots 1 are robust, efficient, and tunable emitters now used in lighting 2-6 , d... more Colloidal quantum dots 1 are robust, efficient, and tunable emitters now used in lighting 2-6 , displays 7 , and lasers 8-11. Consequently, when the spaser 12-a laser-like source of surface plasmons-was first proposed 13 , quantum dots were specified as the ideal plasmonic gain medium. Subsequent spaser designs 14-17 , however, have required a single material to simultaneously provide gain and define the plasmonic cavity, an approach ill-suited to quantum dots and other colloidal nanomaterials. Here we develop a more open architecture that decouples the gain medium from the cavity, leading to a versatile class of quantum-dot-based spasers that allow controlled generation, extraction, and manipulation of plasmons. We first create high-qualityfactor, aberration-corrected, Ag plasmonic cavities. We then incorporate quantum dots via electrohydrodynamic printing 18,19 or drop-casting. Photoexcitation under ambient conditions generates monochromatic plasmons above threshold. This signal is extracted, directed through an integrated amplifier, and focused at a nearby nanoscale tip, generating intense electromagnetic fields. This spaser platform, deployable at different wavelengths, size scales, and geometries, can enable more complex on-chip plasmonic devices.

The Nanoengineering of Highly Conductive or Light-Emitting Structures Through Direct Electrohydrodynamic Printing

3D electrohydrodynamic printing and characterisation of highly conductive gold nanowalls

Nanoscale

Electrohydrodynamically printed high-aspect-ratio gold nanowalls with resistivities down to 2.5× ... more

Metals by Micro‐Scale Additive Manufacturing: Comparison of Microstructure and Mechanical Properties

Advanced Functional Materials

A customizable class of colloidal-quantum-dot spasers and plasmonic amplifiers

Science Advances, Sep 1, 2017

Colloidal quantum dots are robust, efficient, and tunable emitters now used in lighting, displays... more Colloidal quantum dots are robust, efficient, and tunable emitters now used in lighting, displays, and lasers. Consequently, when the spaser-a laser-like source of high-intensity, narrow-band surface plasmons-was first proposed, quantum dots were specified as the ideal plasmonic gain medium for overcoming the significant intrinsic losses of plasmons. Many subsequent spasers, however, have required a single material to simultaneously provide gain and define the plasmonic cavity, a design unable to accommodate quantum dots and other colloidal nanomaterials. In addition, these and other designs have been ill suited for integration with other elements in a larger plasmonic circuit, limiting their use. We develop a more open architecture that decouples the gain medium from the cavity, leading to a versatile class of quantum dot-based spasers that allow controlled generation, extraction, and manipulation of plasmons. We first create aberration-corrected plasmonic cavities with high quality factors at desired locations on an ultrasmooth silver substrate. We then incorporate quantum dots into these cavities via electrohydrodynamic printing or drop-casting. Photoexcitation under ambient conditions generates monochromatic plasmons (0.65-nm linewidth at 630 nm, Q~1000) above threshold. This signal is extracted, directed through an integrated amplifier, and focused at a nearby nanoscale tip, generating intense electromagnetic fields. More generally, our device platform can be straightforwardly deployed at different wavelengths, size scales, and geometries on large-area plasmonic chips for fundamental studies and applications.

Nanoprinting organic molecules at the quantum level

Nature Communications, Apr 23, 2019

Organic compounds present a powerful platform for nanotechnological applications. In particular, ... more Organic compounds present a powerful platform for nanotechnological applications. In particular, molecules suitable for optical functionalities such as single photon generation and energy transfer have great promise for complex nanophotonic circuitry due to their large variety of spectral properties, efficient absorption and emission, and ease of synthesis. Optimal integration, however, calls for control over position and orientation of individual molecules. While various methods have been explored for reaching this regime in the past, none satisfies requirements necessary for practical applications. Here, we present direct noncontact electrohydrodynamic nanoprinting of a countable number of photostable and oriented molecules in a nanocrystal host with subwavelength positioning accuracy. We demonstrate the power of our approach by writing arbitrary patterns and controlled coupling of single molecules to the near field of optical nanostructures. Placement precision, high yield and fabrication facility of our method open many doors for the realization of novel nanophotonic devices.

Defect-Tolerant Plasmonic Elliptical Resonators for Long-Range Energy Transfer

ACS Nano, Jul 11, 2019

Two-or four-inch diameter, single-side-polished, single-crystalline Si(100) wafers with <0.4 nm r... more Two-or four-inch diameter, single-side-polished, single-crystalline Si(100) wafers with <0.4 nm root-mean-square (RMS) roughness and thicknesses of 1000 μm were purchased from Silicon Valley Microelectronics or Silicon Quest. Four-inch wafers were diced into 2 × 2 cm 2 or 1.5 × 1.5 cm 2 square pieces. Sulfuric acid (H2SO4, 95-98%, 258105) was purchased from Sigma. Hydrogen peroxide (H2O2, 30%, AnalaR Normapur) was bought from VWR. Nitric Acid (65% HNO3) was acquired from Fisher Chemical. 18.2 MΩ deionized water (DI) was obtained from a MilliQ Advantage A10 waterpurification system. Silver (Ag, 99.999%) pellets were purchased from Kurt Lesker. Tungsten dimple boats (49 × 12 × 0.4 mm 3) were bought from Umicore. Acetone (Technic France, Micropur VLSI Grade),

Defect-Tolerant Plasmonic Elliptical Resonators for Long-Range Energy Transfer

ACS Nano

Two-or four-inch diameter, single-side-polished, single-crystalline Si(100) wafers with <0.4 nm r... more Two-or four-inch diameter, single-side-polished, single-crystalline Si(100) wafers with <0.4 nm root-mean-square (RMS) roughness and thicknesses of 1000 μm were purchased from Silicon Valley Microelectronics or Silicon Quest. Four-inch wafers were diced into 2 × 2 cm 2 or 1.5 × 1.5 cm 2 square pieces. Sulfuric acid (H2SO4, 95-98%, 258105) was purchased from Sigma. Hydrogen peroxide (H2O2, 30%, AnalaR Normapur) was bought from VWR. Nitric Acid (65% HNO3) was acquired from Fisher Chemical. 18.2 MΩ deionized water (DI) was obtained from a MilliQ Advantage A10 waterpurification system. Silver (Ag, 99.999%) pellets were purchased from Kurt Lesker. Tungsten dimple boats (49 × 12 × 0.4 mm 3) were bought from Umicore. Acetone (Technic France, Micropur VLSI Grade),

Nanoprinting organic molecules at the quantum level

Nature Communications

Organic compounds present a powerful platform for nanotechnological applications. In particular, ... more Organic compounds present a powerful platform for nanotechnological applications. In particular, molecules suitable for optical functionalities such as single photon generation and energy transfer have great promise for complex nanophotonic circuitry due to their large variety of spectral properties, efficient absorption and emission, and ease of synthesis. Optimal integration, however, calls for control over position and orientation of individual molecules. While various methods have been explored for reaching this regime in the past, none satisfies requirements necessary for practical applications. Here, we present direct noncontact electrohydrodynamic nanoprinting of a countable number of photostable and oriented molecules in a nanocrystal host with subwavelength positioning accuracy. We demonstrate the power of our approach by writing arbitrary patterns and controlled coupling of single molecules to the near field of optical nanostructures. Placement precision, high yield and fabrication facility of our method open many doors for the realization of novel nanophotonic devices.

Multi-metal electrohydrodynamic redox 3D printing at the submicron scale

Nature Communications

An extensive range of metals can be dissolved and re-deposited in liquid solvents using electroch... more An extensive range of metals can be dissolved and re-deposited in liquid solvents using electrochemistry. We harness this concept for additive manufacturing, demonstrating the focused electrohydrodynamic ejection of metal ions dissolved from sacrificial anodes and their subsequent reduction to elemental metals on the substrate. This technique, termed electrohydrodynamic redox printing (EHD-RP), enables the direct, ink-free fabrication of polycrystalline multi-metal 3D structures without the need for post-print processing. On-thefly switching and mixing of two metals printed from a single multichannel nozzle facilitates a chemical feature size of <400 nm with a spatial resolution of 250 nm at printing speeds of up to 10 voxels per second. As shown, the additive control of the chemical architecture of materials provided by EHD-RP unlocks the synthesis of 3D bi-metal structures with programmed local properties and opens new avenues for the direct fabrication of chemically architected materials and devices.

Two-Dimensional Drexhage Experiment for Electric- and Magnetic-Dipole Sources on Plasmonic Interfaces

Physical Review Letters

Generation of single optical plasmons in metallic nanowires coupled to quantum dots, Nature (Lond... more

A customizable class of colloidal-quantum-dot spasers and plasmonic amplifiers

Science Advances

Colloidal quantum dots are robust, efficient, and tunable emitters now used in lighting, displays... more Colloidal quantum dots are robust, efficient, and tunable emitters now used in lighting, displays, and lasers. Consequently, when the spaser-a laser-like source of high-intensity, narrow-band surface plasmons-was first proposed, quantum dots were specified as the ideal plasmonic gain medium for overcoming the significant intrinsic losses of plasmons. Many subsequent spasers, however, have required a single material to simultaneously provide gain and define the plasmonic cavity, a design unable to accommodate quantum dots and other colloidal nanomaterials. In addition, these and other designs have been ill suited for integration with other elements in a larger plasmonic circuit, limiting their use. We develop a more open architecture that decouples the gain medium from the cavity, leading to a versatile class of quantum dot-based spasers that allow controlled generation, extraction, and manipulation of plasmons. We first create aberration-corrected plasmonic cavities with high quality factors at desired locations on an ultrasmooth silver substrate. We then incorporate quantum dots into these cavities via electrohydrodynamic printing or drop-casting. Photoexcitation under ambient conditions generates monochromatic plasmons (0.65-nm linewidth at 630 nm, Q~1000) above threshold. This signal is extracted, directed through an integrated amplifier, and focused at a nearby nanoscale tip, generating intense electromagnetic fields. More generally, our device platform can be straightforwardly deployed at different wavelengths, size scales, and geometries on large-area plasmonic chips for fundamental studies and applications.

Transparent Electrodes: Electrohydrodynamic NanoDrip Printing of High Aspect Ratio Metal Grid Transparent Electrodes (Adv. Funct. Mater. 6/2016)

Advanced Functional Materials, 2016

Colloidal-quantum-dot spasers and plasmonic amplifiers

arXiv (Cornell University), Nov 29, 2016

Colloidal quantum dots 1 are robust, efficient, and tunable emitters now used in lighting 2-6 , d... more Colloidal quantum dots 1 are robust, efficient, and tunable emitters now used in lighting 2-6 , displays 7 , and lasers 8-11. Consequently, when the spaser 12-a laser-like source of surface plasmons-was first proposed 13 , quantum dots were specified as the ideal plasmonic gain medium. Subsequent spaser designs 14-17 , however, have required a single material to simultaneously provide gain and define the plasmonic cavity, an approach ill-suited to quantum dots and other colloidal nanomaterials. Here we develop a more open architecture that decouples the gain medium from the cavity, leading to a versatile class of quantum-dot-based spasers that allow controlled generation, extraction, and manipulation of plasmons. We first create high-qualityfactor, aberration-corrected, Ag plasmonic cavities. We then incorporate quantum dots via electrohydrodynamic printing 18,19 or drop-casting. Photoexcitation under ambient conditions generates monochromatic plasmons above threshold. This signal is extracted, directed through an integrated amplifier, and focused at a nearby nanoscale tip, generating intense electromagnetic fields. This spaser platform, deployable at different wavelengths, size scales, and geometries, can enable more complex on-chip plasmonic devices.

Acoustic Metal Particle Focusing in a Round Glass Capillary

arXiv (Cornell University), May 24, 2021

Two-dimensional metal particle focusing is an essential task for various fabrication processes. W... more Two-dimensional metal particle focusing is an essential task for various fabrication processes. While acoustofluidic devices can manipulate particles in two dimensions, the production of these devices often demands a cleanroom environment. Therefore, acoustically excited glass capillaries present a cheap alternative to labour-intensive cleanroom production. Here, we present 2D metal micro-particle focusing in a round glass capillary using bulk acoustic waves. Excitation of the piezoelectric transducer at specific frequencies leads to mode shapes in the round capillary, concentrating particles towards the capillary centre. We experimentally investigate the particle linewidth for different particle materials and concentrations. We demonstrate the focus of copper particles with ∼ 1 µm in diameter down to a line of width 60.8 ± 7.0 µm and height 45.2 ± 9.3 µm, corresponding to a local concentration of 4.5 % v/v, which is 90 times higher than the concentration of the initial solution. Through numerical analysis, we could obtain further insights into the particle manipulation mechanism inside the capillary and predict the particle trajectories. We found that a transition of the acoustic streaming pattern enables us to manipulate particles close to the critical particle radius. Finally, we used our method to eject copper particles through a tapered round capillary with an opening of 25 µm in diameter, which would not be possible without particle focusing. Our novel setup can be utilized for various applications, that otherwise might suffer from abrasion, clogging and limited resolution.

Acoustic Metal Particle Focusing in a Round Glass Capillary

arXiv (Cornell University), May 24, 2021

Two-dimensional metal particle focusing is an essential task for various fabrication processes. W... more Two-dimensional metal particle focusing is an essential task for various fabrication processes. While acoustofluidic devices can manipulate particles in two dimensions, the production of these devices often demands a cleanroom environment. Therefore, acoustically excited glass capillaries present a cheap alternative to labour-intensive cleanroom production. Here, we present 2D metal micro-particle focusing in a round glass capillary using bulk acoustic waves. Excitation of the piezoelectric transducer at specific frequencies leads to mode shapes in the round capillary, concentrating particles towards the capillary centre. We experimentally investigate the particle linewidth for different particle materials and concentrations. We demonstrate the focus of copper particles with ∼ 1 µm in diameter down to a line of width 60.8 ± 7.0 µm and height 45.2 ± 9.3 µm, corresponding to a local concentration of 4.5 % v/v, which is 90 times higher than the concentration of the initial solution. Through numerical analysis, we could obtain further insights into the particle manipulation mechanism inside the capillary and predict the particle trajectories. We found that a transition of the acoustic streaming pattern enables us to manipulate particles close to the critical particle radius. Finally, we used our method to eject copper particles through a tapered round capillary with an opening of 25 µm in diameter, which would not be possible without particle focusing. Our novel setup can be utilized for various applications, that otherwise might suffer from abrasion, clogging and limited resolution.

Focusing of Micrometer-Sized Metal Particles Enabled by Reduced Acoustic Streaming via Acoustic Forces in a Round Glass Capillary

Physical Review Applied, 2022

This page was generated automatically upon download from the ETH Zurich Research Collection. For ... more

Deterministic Nanoprinting of Single Fluorescent Molecules

We report direct non-contact electrohydrodynamic nanodrip printing of a countable number of photo... more

Zusammenfassung Numerische Mathematik

Probing Electromagnetic Modes at Optical Frequencies with Eu3+-Doped Nanocrystals

Proceedings of the nanoGe Fall Meeting 2018

Colloidal Quantum-Dot Spasers and Plasmonic Amplifiers

Advanced Photonics 2017 (IPR, NOMA, Sensors, Networks, SPPCom, PS), 2017

Colloidal quantum dots 1 are robust, efficient, and tunable emitters now used in lighting 2-6 , d... more Colloidal quantum dots 1 are robust, efficient, and tunable emitters now used in lighting 2-6 , displays 7 , and lasers 8-11. Consequently, when the spaser 12-a laser-like source of surface plasmons-was first proposed 13 , quantum dots were specified as the ideal plasmonic gain medium. Subsequent spaser designs 14-17 , however, have required a single material to simultaneously provide gain and define the plasmonic cavity, an approach ill-suited to quantum dots and other colloidal nanomaterials. Here we develop a more open architecture that decouples the gain medium from the cavity, leading to a versatile class of quantum-dot-based spasers that allow controlled generation, extraction, and manipulation of plasmons. We first create high-qualityfactor, aberration-corrected, Ag plasmonic cavities. We then incorporate quantum dots via electrohydrodynamic printing 18,19 or drop-casting. Photoexcitation under ambient conditions generates monochromatic plasmons above threshold. This signal is extracted, directed through an integrated amplifier, and focused at a nearby nanoscale tip, generating intense electromagnetic fields. This spaser platform, deployable at different wavelengths, size scales, and geometries, can enable more complex on-chip plasmonic devices.

The Nanoengineering of Highly Conductive or Light-Emitting Structures Through Direct Electrohydrodynamic Printing

3D electrohydrodynamic printing and characterisation of highly conductive gold nanowalls

Nanoscale

Electrohydrodynamically printed high-aspect-ratio gold nanowalls with resistivities down to 2.5× ... more

Metals by Micro‐Scale Additive Manufacturing: Comparison of Microstructure and Mechanical Properties

Advanced Functional Materials

A customizable class of colloidal-quantum-dot spasers and plasmonic amplifiers

Science Advances, Sep 1, 2017

Colloidal quantum dots are robust, efficient, and tunable emitters now used in lighting, displays... more Colloidal quantum dots are robust, efficient, and tunable emitters now used in lighting, displays, and lasers. Consequently, when the spaser-a laser-like source of high-intensity, narrow-band surface plasmons-was first proposed, quantum dots were specified as the ideal plasmonic gain medium for overcoming the significant intrinsic losses of plasmons. Many subsequent spasers, however, have required a single material to simultaneously provide gain and define the plasmonic cavity, a design unable to accommodate quantum dots and other colloidal nanomaterials. In addition, these and other designs have been ill suited for integration with other elements in a larger plasmonic circuit, limiting their use. We develop a more open architecture that decouples the gain medium from the cavity, leading to a versatile class of quantum dot-based spasers that allow controlled generation, extraction, and manipulation of plasmons. We first create aberration-corrected plasmonic cavities with high quality factors at desired locations on an ultrasmooth silver substrate. We then incorporate quantum dots into these cavities via electrohydrodynamic printing or drop-casting. Photoexcitation under ambient conditions generates monochromatic plasmons (0.65-nm linewidth at 630 nm, Q~1000) above threshold. This signal is extracted, directed through an integrated amplifier, and focused at a nearby nanoscale tip, generating intense electromagnetic fields. More generally, our device platform can be straightforwardly deployed at different wavelengths, size scales, and geometries on large-area plasmonic chips for fundamental studies and applications.

Nanoprinting organic molecules at the quantum level

Nature Communications, Apr 23, 2019

Organic compounds present a powerful platform for nanotechnological applications. In particular, ... more Organic compounds present a powerful platform for nanotechnological applications. In particular, molecules suitable for optical functionalities such as single photon generation and energy transfer have great promise for complex nanophotonic circuitry due to their large variety of spectral properties, efficient absorption and emission, and ease of synthesis. Optimal integration, however, calls for control over position and orientation of individual molecules. While various methods have been explored for reaching this regime in the past, none satisfies requirements necessary for practical applications. Here, we present direct noncontact electrohydrodynamic nanoprinting of a countable number of photostable and oriented molecules in a nanocrystal host with subwavelength positioning accuracy. We demonstrate the power of our approach by writing arbitrary patterns and controlled coupling of single molecules to the near field of optical nanostructures. Placement precision, high yield and fabrication facility of our method open many doors for the realization of novel nanophotonic devices.

Defect-Tolerant Plasmonic Elliptical Resonators for Long-Range Energy Transfer

ACS Nano, Jul 11, 2019

Two-or four-inch diameter, single-side-polished, single-crystalline Si(100) wafers with <0.4 nm r... more Two-or four-inch diameter, single-side-polished, single-crystalline Si(100) wafers with <0.4 nm root-mean-square (RMS) roughness and thicknesses of 1000 μm were purchased from Silicon Valley Microelectronics or Silicon Quest. Four-inch wafers were diced into 2 × 2 cm 2 or 1.5 × 1.5 cm 2 square pieces. Sulfuric acid (H2SO4, 95-98%, 258105) was purchased from Sigma. Hydrogen peroxide (H2O2, 30%, AnalaR Normapur) was bought from VWR. Nitric Acid (65% HNO3) was acquired from Fisher Chemical. 18.2 MΩ deionized water (DI) was obtained from a MilliQ Advantage A10 waterpurification system. Silver (Ag, 99.999%) pellets were purchased from Kurt Lesker. Tungsten dimple boats (49 × 12 × 0.4 mm 3) were bought from Umicore. Acetone (Technic France, Micropur VLSI Grade),

Defect-Tolerant Plasmonic Elliptical Resonators for Long-Range Energy Transfer

ACS Nano

Two-or four-inch diameter, single-side-polished, single-crystalline Si(100) wafers with <0.4 nm r... more Two-or four-inch diameter, single-side-polished, single-crystalline Si(100) wafers with <0.4 nm root-mean-square (RMS) roughness and thicknesses of 1000 μm were purchased from Silicon Valley Microelectronics or Silicon Quest. Four-inch wafers were diced into 2 × 2 cm 2 or 1.5 × 1.5 cm 2 square pieces. Sulfuric acid (H2SO4, 95-98%, 258105) was purchased from Sigma. Hydrogen peroxide (H2O2, 30%, AnalaR Normapur) was bought from VWR. Nitric Acid (65% HNO3) was acquired from Fisher Chemical. 18.2 MΩ deionized water (DI) was obtained from a MilliQ Advantage A10 waterpurification system. Silver (Ag, 99.999%) pellets were purchased from Kurt Lesker. Tungsten dimple boats (49 × 12 × 0.4 mm 3) were bought from Umicore. Acetone (Technic France, Micropur VLSI Grade),

Nanoprinting organic molecules at the quantum level

Nature Communications

Organic compounds present a powerful platform for nanotechnological applications. In particular, ... more Organic compounds present a powerful platform for nanotechnological applications. In particular, molecules suitable for optical functionalities such as single photon generation and energy transfer have great promise for complex nanophotonic circuitry due to their large variety of spectral properties, efficient absorption and emission, and ease of synthesis. Optimal integration, however, calls for control over position and orientation of individual molecules. While various methods have been explored for reaching this regime in the past, none satisfies requirements necessary for practical applications. Here, we present direct noncontact electrohydrodynamic nanoprinting of a countable number of photostable and oriented molecules in a nanocrystal host with subwavelength positioning accuracy. We demonstrate the power of our approach by writing arbitrary patterns and controlled coupling of single molecules to the near field of optical nanostructures. Placement precision, high yield and fabrication facility of our method open many doors for the realization of novel nanophotonic devices.

Multi-metal electrohydrodynamic redox 3D printing at the submicron scale

Nature Communications

An extensive range of metals can be dissolved and re-deposited in liquid solvents using electroch... more An extensive range of metals can be dissolved and re-deposited in liquid solvents using electrochemistry. We harness this concept for additive manufacturing, demonstrating the focused electrohydrodynamic ejection of metal ions dissolved from sacrificial anodes and their subsequent reduction to elemental metals on the substrate. This technique, termed electrohydrodynamic redox printing (EHD-RP), enables the direct, ink-free fabrication of polycrystalline multi-metal 3D structures without the need for post-print processing. On-thefly switching and mixing of two metals printed from a single multichannel nozzle facilitates a chemical feature size of <400 nm with a spatial resolution of 250 nm at printing speeds of up to 10 voxels per second. As shown, the additive control of the chemical architecture of materials provided by EHD-RP unlocks the synthesis of 3D bi-metal structures with programmed local properties and opens new avenues for the direct fabrication of chemically architected materials and devices.

Two-Dimensional Drexhage Experiment for Electric- and Magnetic-Dipole Sources on Plasmonic Interfaces

Physical Review Letters

Generation of single optical plasmons in metallic nanowires coupled to quantum dots, Nature (Lond... more

A customizable class of colloidal-quantum-dot spasers and plasmonic amplifiers

Science Advances

Colloidal quantum dots are robust, efficient, and tunable emitters now used in lighting, displays... more Colloidal quantum dots are robust, efficient, and tunable emitters now used in lighting, displays, and lasers. Consequently, when the spaser-a laser-like source of high-intensity, narrow-band surface plasmons-was first proposed, quantum dots were specified as the ideal plasmonic gain medium for overcoming the significant intrinsic losses of plasmons. Many subsequent spasers, however, have required a single material to simultaneously provide gain and define the plasmonic cavity, a design unable to accommodate quantum dots and other colloidal nanomaterials. In addition, these and other designs have been ill suited for integration with other elements in a larger plasmonic circuit, limiting their use. We develop a more open architecture that decouples the gain medium from the cavity, leading to a versatile class of quantum dot-based spasers that allow controlled generation, extraction, and manipulation of plasmons. We first create aberration-corrected plasmonic cavities with high quality factors at desired locations on an ultrasmooth silver substrate. We then incorporate quantum dots into these cavities via electrohydrodynamic printing or drop-casting. Photoexcitation under ambient conditions generates monochromatic plasmons (0.65-nm linewidth at 630 nm, Q~1000) above threshold. This signal is extracted, directed through an integrated amplifier, and focused at a nearby nanoscale tip, generating intense electromagnetic fields. More generally, our device platform can be straightforwardly deployed at different wavelengths, size scales, and geometries on large-area plasmonic chips for fundamental studies and applications.

Transparent Electrodes: Electrohydrodynamic NanoDrip Printing of High Aspect Ratio Metal Grid Transparent Electrodes (Adv. Funct. Mater. 6/2016)

Advanced Functional Materials, 2016