15 research outputs found
Nanoscale Manipulation, Probing, and Assembly Using Microfluidic Flow Control
Nanoparticles have unique properties that can be beneficial in fields ranging from quantum information to biological sensing. To take advantage of some of some of these benefits, techniques are required that can select single particles and place them at desired locations with nanoscale precision. This capability allows for bottom-up assembly of nanoparticle systems and facilitates development of improved tools for probing nanoscale physics. Current manipulation approaches are inadequate for positioning nanoparticles such as single quantum dots. Quantum dots can act as single photon sources, and are useful for applications in nanophotonics and quantum optics. In this thesis, I present a technique for manipulation of single quantum dots and other nano-objects. Using this technique, I demonstrate nanoparticle manipulation, assembly, and probing with nanoscale precision.
The nanomanipulation approach I introduce employs electroosmotic flow to position colloidal nanoparticles suspended in an aqueous system. Single quantum dot manipulation is demonstrated with a precision better than 50 nm for holding times of up to one hour. This technique is useful for studying the behavior of single quantum dots and their interactions with the environment in real time. A fluid chemistry was developed for the deterministic immobilization of nanoparticles along a two-dimensional surface with 130 nm precision. In addition, a technique for assembling systems of silver nanowires is demonstrated. A method for imaging the local density of optical states of silver nanowires is presented using single quantum dots as probes, achieving an imaging accuracy of 12 nm. Spontaneous emission control is accomplished simultaneously by placing the quantum dot at various locations along the wire. Together, these experiments illustrate the versatility of microfluidics for the advancement of nanoscience research and engineering
Scalable and Robust Beam Shaping Using Apodized Fish-bone Grating Couplers
Efficient power coupling between on-chip guided and free-space optical modes
requires precision spatial mode matching with apodized grating couplers. Yet,
grating apodizations are often limited by the minimum feature size of the
fabrication approach. This is especially challenging when small feature sizes
are required to fabricate gratings at short wavelengths or to achieve weakly
scattered light for large-area gratings. Here, we demonstrate a fish-bone
grating coupler for precision beam shaping and the generation of
millimeter-scale beams at 461 nm wavelength. Our design decouples the minimum
feature size from the minimum achievable optical scattering strength, allowing
smooth turn-on and continuous control of the emission. Our approach is
compatible with commercial foundry photolithography and has reduced sensitivity
to both the resolution and the variability of the fabrication approach compared
to subwavelength meta-gratings, which often require electron beam lithography.Comment: 10 pages, 6 figure
Emergence of an enslaved phononic bandgap in a non-equilibrium pseudo-crystal
International audienceMaterial systems that reside far from thermodynamic equilibrium have the potential to exhibit dynamic properties and behaviours resembling those of living organisms. Here we realize a non-equilibrium material characterized by a bandgap whose edge is enslaved to the wavelength of an external coherent drive. The structure dynamically self-assembles into an unconventional pseudo-crystal geometry that equally distributes momentum across elements. The emergent bandgap is bestowed with lifelike properties, such as the ability to self-heal to perturbations and adapt to sudden changes in the drive. We derive an exact analytical solution for both the spatial organization and the bandgap features, revealing the mechanism for enslavement. This work presents a framework for conceiving lifelike non-equilibrium materials and emphasizes the potential for the dynamic imprinting of material properties through external degrees of freedom
Manipulating Quantum Dots to Nanometer Precision by Control of Flow
We present a method for manipulating preselected quantum dots (QDs) with nanometer precision by flow control. The accuracy of this approach scales more favorably with particle size than optical trapping, enabling more precise positioning of nanoscopic particles. We demonstrate the ability to position a single QD in a 100 μm working region to 45 nm accuracy for holding times exceeding one hour and the ability to take active quantum measurements on the dynamically manipulated QD.
Keywords:
Quantum dots; control; electroosmotic flow; subpixel averaging; photon antibunchin
Scanning Localized Magnetic Fields in a Microfluidic Device with a Single Nitrogen Vacancy Center
Nitrogen
vacancy (NV) color centers in diamond enable local magnetic
field sensing with high sensitivity by optical detection of electron
spin resonance (ESR). The integration of this capability with microfluidic
technology has a broad range of applications in chemical and biological
sensing. We demonstrate a method to perform localized magnetometry
in a microfluidic device with a 48 nm spatial precision. The device
manipulates individual magnetic particles in three dimensions using
a combination of flow control and magnetic actuation. We map out the
local field distribution of the magnetic particle by manipulating
it in the vicinity of a single NV center and optically detecting the
induced Zeeman shift with a magnetic field sensitivity of 17.5 μT
Hz<sup>–1/2</sup>. Our results enable accurate nanoscale mapping
of the magnetic field distribution of a broad range of target objects
in a microfluidic device
Nanostructure-Induced Distortion in Single-Emitter Microscopy
Single-emitter
microscopy has emerged as a promising method of imaging nanostructures
with nanoscale resolution. This technique uses the centroid position
of an emitter’s far-field radiation pattern to infer its position
to a precision that is far below the diffraction limit. However, nanostructures
composed of high-dielectric materials such as noble metals can distort
the far-field radiation pattern. Previous work has shown that these
distortions can significantly degrade the imaging of the local density
of states in metallic nanowires using polarization-resolved imaging.
But unlike nanowires, nanoparticles do not have a well-defined axis
of symmetry, which makes polarization-resolved imaging difficult to
apply. Nanoparticles also exhibit a more complex range of distortions,
because in addition to introducing a high dielectric surface, they
also act as efficient scatterers. Thus, the distortion effects of
nanoparticles in single-emitter microscopy remains poorly understood.
Here we demonstrate that metallic nanoparticles can significantly
distort the accuracy of single-emitter imaging at distances exceeding
300 nm. We use a single quantum dot to probe both the magnitude and
the direction of the metallic nanoparticle-induced imaging distortion
and show that the diffraction spot of the quantum dot can shift by
more than 35 nm. The centroid position of the emitter generally shifts
away from the nanoparticle position, which is in contradiction to
the conventional wisdom that the nanoparticle is a scattering object
that will pull in the diffraction spot of the emitter toward its center.
These results suggest that dielectric distortion of the emission pattern
dominates over scattering. We also show that by monitoring the distortion
of the quantum dot diffraction spot we can obtain high-resolution
spatial images of the nanoparticle, providing a new method for performing
highly precise, subdiffraction spatial imaging. These results provide
a better understanding of the complex near-field coupling between
emitters and nanostructures and open up new opportunities to perform
super-resolution microscopy with higher accuracy
Integrating planar photonics for multi-beam generation and atomic clock packaging on chip
A planar platform combining photonic integrated circuits and flip-chip bonded meta-surfaces for multi-color light projection, beam shaping, and polarization control for compact laser cooling
Fabrication of Nanoassemblies Using Flow Control
Synthetic nanostructures, such as
nanoparticles and nanowires,
can serve as modular building blocks for integrated nanoscale systems.
We demonstrate a microfluidic approach for positioning, orienting,
and assembling such nanostructures into nanoassemblies. We use flow
control combined with a cross-linking photoresist to position and
immobilize nanostructures in desired positions and orientations. Immobilized
nanostructures can serve as pivots, barriers, and guides for precise
placement of subsequent nanostructures