Willem L. Vos
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View article: Dispersion of backward-propagating waves in a surface defect on a three-dimensional photonic band-gap crystal
Dispersion of backward-propagating waves in a surface defect on a three-dimensional photonic band-gap crystal Open
We experimentally study the dispersion relation of waves in a thin quasi-two-dimensional (2D) defect layer with periodic nanopores that sits on a 3D photonic band-gap crystal made from silicon by CMOS-compatible methods. The nanostructures…
View article: Resolving features and derivatives in data with noise
Resolving features and derivatives in data with noise Open
A frequently occurring challenge in experimental and numerical observation is how to resolve features, such as spectral peaks - with center, width, height - and derivatives from measured data with unavoidable noise. Therefore, we develop a…
View article: Dispersion of backward-propagating waves in a surface defect on a 3D photonic band gap crystal
Dispersion of backward-propagating waves in a surface defect on a 3D photonic band gap crystal Open
We experimentally study the dispersion relation of waves in a two-dimensional (2D) defect layer with periodic nanopores that sits on a three-dimensional (3D) photonic band gap crystal made from silicon by CMOS-compatible methods. The nanos…
View article: Fabrication of 3D photonic band gap crystals for controlling the emission of light
Fabrication of 3D photonic band gap crystals for controlling the emission of light Open
3D photonic band gap crystals can be used to manipulate light, for example to increase the emission of an emitter. An inverse woodpile photonic band gap crystal has been fabricated in silicon by FIB lithography and reactive ion etching. Th…
View article: Wavefront Shaping with Varying Degrees of Freedom
Wavefront Shaping with Varying Degrees of Freedom Open
Optical wavefront shaping employs the linearity of scattering to focus light through scattering media using spatial modulation. By selectively switching off weakly-contributing segments, we significantly improve optimization speeds with mi…
View article: Mesoscopic theory of optical wavefront shaping to focus deep inside opaque media
Mesoscopic theory of optical wavefront shaping to focus deep inside opaque media Open
We describe the theory of optical wavefront shaping, where waves are focused to a predefined focal point deep inside a disordered three-dimensional (3D) opaque medium ( e.g. , tissue, paint, foam) by shaping the wavefield sent by N externa…
View article: Observation of Cartesian light propagation through a three-dimensional cavity superlattice in a silicon photonic band gap crystal
Observation of Cartesian light propagation through a three-dimensional cavity superlattice in a silicon photonic band gap crystal Open
We experimentally investigate peculiar light propagation inside a three-dimensional (3D) superlattice of resonant cavities that are confined within a 3D photonic band gap. To this end, we fabricated 3D diamondlike photonic crystals from si…
View article: Mesoscopic Theory of Wavefront Shaping to Focus Waves inside Disordered Media
Mesoscopic Theory of Wavefront Shaping to Focus Waves inside Disordered Media Open
We describe the {theory of focusing waves} to a predefined spatial point {inside} a disordered {three-dimensional medium} by the external shaping of {$N$} different field sources outside the medium, {also known as wavefront shaping}. We {d…
View article: Probing the position-dependent optical energy fluence rate in three-dimensional scattering samples
Probing the position-dependent optical energy fluence rate in three-dimensional scattering samples Open
The accurate determination of the position-dependent energy fluence rate of scattered light (which is proportional to the energy density) is crucial to the understanding of transport in anisotropically scattering and absorbing samples, suc…
View article: Experimentally mapping the scattering phases and amplitudes of a finite object by optical mutual scattering
Experimentally mapping the scattering phases and amplitudes of a finite object by optical mutual scattering Open
Mutual scattering arises when multiple waves intersect within a finite scattering object, resulting in cross-interference between the incident and scattered waves. By measuring mutual scattering, we determine the complex-valued scattering …
View article: Symmetries and wave functions of photons confined in three-dimensional photonic band gap superlattices
Symmetries and wave functions of photons confined in three-dimensional photonic band gap superlattices Open
We perform a computational study of confined photonic states that appear in a three-dimensional (3D) superlattice of coupled cavities, resulting from a superstructure of intentional defects. The states are isolated from the vacuum by a 3D …
View article: Strongly Inhibited Spontaneous Emission of PbS Quantum Dots Covalently Bound to 3D Silicon Photonic Band Gap Crystals
Strongly Inhibited Spontaneous Emission of PbS Quantum Dots Covalently Bound to 3D Silicon Photonic Band Gap Crystals Open
We present an optical study of the spontaneous emission of lead sulfide (PbS) nanocrystal quantum dots in 3D photonic band gap crystals made from silicon. The nanocrystals emit in the near-infrared range to be compatible with 3D silicon na…
View article: Non-utopian optical properties computed of a tomographically reconstructed real photonic nanostructure
Non-utopian optical properties computed of a tomographically reconstructed real photonic nanostructure Open
State-of-the-art computational methods combined with common idealized structural models provide an incomplete understanding of experimental observations on real nanostructures, since manufacturing introduces unavoidable deviations from the…
View article: Non-utopian optical properties computed of a tomographically reconstructed real photonic nanostructure
Non-utopian optical properties computed of a tomographically reconstructed real photonic nanostructure Open
State-of-the-art computational methods combined with common idealized structural models provide an incomplete understanding of experiments on real nanostructures, since manufacturing introduces unavoidable deviations from the design. We pr…
View article: Probing the position-dependent optical energy fluence rate in three-dimensional scattering samples
Probing the position-dependent optical energy fluence rate in three-dimensional scattering samples Open
The accurate determination of the position-dependent energy fluence rate of scattered light (which is proportional to the energy density) is crucial to the understanding of transport in anisotropically scattering and absorbing samples, suc…
View article: Wavefront shaping through a free-form scattering object
Wavefront shaping through a free-form scattering object Open
Wavefront shaping is a technique to study and control light transport inside scattering media. Wavefront shaping is considered to be applicable to any complex material, yet in most previous studies, the only sample geometries that are stud…
View article: Generation of ultrashort (~10ps) spontaneous emission pulses by quantum dots in a switched optical microcavity
Generation of ultrashort (~10ps) spontaneous emission pulses by quantum dots in a switched optical microcavity Open
We report on the generation of few-ps long spontaneous emission pulses by quantum dots (QDs) in a switched optical microcavity. We use a pulsed optical injection of free charge carriers to induce a large frequency shift of the fundamental …
View article: Symmetries and Wavefunctions of Photons Confined in 3D Photonic Band Gap Superlattices
Symmetries and Wavefunctions of Photons Confined in 3D Photonic Band Gap Superlattices Open
We perform a computational study of confined photonic states that appear in a three-dimensional (3D) superlattice of coupled cavities, resulting from a superstructure of intentional defects. The states are isolated from the vacuum by a 3D …
View article: Strongly inhibited spontaneous emission of PbS quantum dots covalently bound to 3D silicon photonic band gap crystals
Strongly inhibited spontaneous emission of PbS quantum dots covalently bound to 3D silicon photonic band gap crystals Open
We present an optical study of the spontaneous emission of lead sulfide (PbS) nanocrystal quantum dots in three-dimensional (3D) photonic band gap crystals made from silicon. The nanocrystals emit in the near-infrared (NIR) range to be com…
View article: Wavefront shaping through a free-form scattering object
Wavefront shaping through a free-form scattering object Open
Wavefront shaping is a technique to study and control light transport inside scattering media. Wavefront shaping is considered to be applicable to any complex material, yet in most previous studies, the only sample geometries that are stud…
View article: Computation of Optical Properties of Real Photonic Band Gap Crystals as Opposed to Utopian Ones
Computation of Optical Properties of Real Photonic Band Gap Crystals as Opposed to Utopian Ones Open
Computational methods are essential in the design and analysis of three-dimensional (3D) photonic crystals [1]. These methods predict the physical properties of a particular design before elaborate nanomanufacturing. However, any manufactu…
View article: Enhanced secrecy in optical communication using speckle from multiple scattering layers
Enhanced secrecy in optical communication using speckle from multiple scattering layers Open
We study the secrecy of an optical communication system with two scattering layers, to hide both the sender and receiver, by measuring the correlation of the intermediate speckle generated between the two layers. The binary message is modu…
View article: Unsupervised machine learning to classify the confinement of waves in periodic superstructures
Unsupervised machine learning to classify the confinement of waves in periodic superstructures Open
We propose a rigorous method to classify the dimensionality of wave confinement by utilizing unsupervised machine learning to enhance the accuracy of our recently presented scaling method [ Phys. Rev. Lett. 129 , 176401 ( 2022 ) 10.1103/Ph…
View article: Unsupervised Machine Learning to Classify the Confinement of Waves in Periodic Superstructures
Unsupervised Machine Learning to Classify the Confinement of Waves in Periodic Superstructures Open
We employ unsupervised machine learning to enhance the accuracy of our recently presented scaling method for wave confinement analysis [1]. We employ the standard k-means++ algorithm as well as our own model-based algorithm. We investigate…
View article: Observation of light propagation through a three-dimensional cavity superlattice in a 3D photonic band gap
Observation of light propagation through a three-dimensional cavity superlattice in a 3D photonic band gap Open
We experimentally investigate unusual light propagation inside a three-dimensional (3D) superlattice of resonant cavities that are confined within a 3D photonic band gap. Therefore, we fabricated 3D diamond-like photonic crystals from sili…
View article: Sensing the position of a single scatterer in an opaque medium by mutual scattering
Sensing the position of a single scatterer in an opaque medium by mutual scattering Open
We investigate the potential of mutual scattering, i.e., light scattering with multiple properly phased incident beams, as a method to extract structural information from inside an opaque object. In particular, we study how sensitively the…
View article: Deep reactive ion etching of cylindrical nanopores in silicon for photonic crystals
Deep reactive ion etching of cylindrical nanopores in silicon for photonic crystals Open
Periodic arrays of deep nanopores etched in silicon by deep reactive ion etching are desirable structures for photonic crystals and other nanostructures for silicon nanophotonics. Previous studies focused on realizing as deep as possible n…
View article: Deep Reactive Ion Etching of Cylindrical Nanopores in Silicon for Photonic Crystals
Deep Reactive Ion Etching of Cylindrical Nanopores in Silicon for Photonic Crystals Open
Periodic arrays of deep nanopores etched in silicon by deep reactive ion etching are desirable structures for photonic crystals and other nanostructure for silicon nanophotonics. Previous studies focused on realizing as deep as possible na…
View article: Controlled light scattering of a single nanoparticle by wave-front shaping
Controlled light scattering of a single nanoparticle by wave-front shaping Open
Controlling light scattering by nanoparticles is fundamentally important for the understanding and the control of light with photonic nanostructures, as well as for nanoparticle scattering itself, including Mie scattering. Here, we theoret…