Damascene copper electroplating for on-chip interconnections, a process that we conceived and developed in the early 1990s, makes it possible to fill submicron trenches and vias with copper without creating a void or a seam and has thus proven superior to other technologies of copper deposition. We discuss here the relationship of additives in the plating bath to superfilling, the phenomenon that results in superconformal coverage, and we present a numerical model which accounts for the experimentally observed profile evolution of the plated metal.

Damascene copper electroplating for chip interconnections

Understanding how light interacts with matter at the nanometre scale is a fundamental issue in optoelectronics and nanophotonics. In particular, many applications (such as bio-sensing, cancer therapy and all-optical signal processing) rely on surface-bound optical excitations in metallic nanoparticles. However, so far no experimental technique has been capable of imaging localized optical excitations with sufficient resolution to reveal their dramatic spatial variation over one single nanoparticle. Here, we present a novel method applied on silver nanotriangles, achieving such resolution by recording maps of plasmons in the near-infrared/visible/ultraviolet domain using electron beams instead of photons. This method relies on the detection of plasmons as resonance peaks in the energy-loss spectra of subnanometre electron beams rastered on nanoparticles of well-defined geometrical parameters. This represents a significant improvement in the spatial resolution with which plasmonic modes can be imaged, and provides a powerful tool in the development of nanometre-level optics.

Mapping surface plasmons on a single metallic nanoparticle

https://physicstoday.scitation.org/doi/pdf/10.1063/1.3047693

Introduction to the Theory of Coherence and Polarization of Light

Control over the dispersion of the refractive index is essential to the performance of most modern optical systems. These range from laboratory microscopes to optical fibres and even consumer products, such as photography cameras. Conventional methods of engineering optical dispersion are based on altering material composition, but this process is time-consuming and difficult, and the resulting optical performance is often limited to a certain bandwidth. Recent advances in nanofabrication have led to high-quality metasurfaces with the potential to perform at a level comparable to their state-of-the-art refractive counterparts. In this Review, we introduce the underlying physical principles of metasurface optical elements (with a focus on metalenses) and, drawing on various works in the literature, discuss how their constituent nanostructures can be designed with a highly customizable effective index of refraction that incorporates both phase and dispersion engineering. These metasurfaces can serve as an essential component for achromatic optics with unprecedented levels of performance across a broad bandwidth or provide highly customized, engineered chromatic behaviour in instruments such as miniature aberration-corrected spectrometers. We identify some key areas in which these achromatic or dispersion-engineered metasurface optical elements could be useful and highlight some future challenges, as well as promising ways to overcome them. Flat metasurface optics provides an emerging platform for combining semiconductor foundry methods of manufacturing and assembling with nanophotonics to produce high-end and multifunctional optical elements. This Review highlights the design of metasurfaces, recent advances in the field and initial promising applications.

Flat optics with dispersion-engineered metasurfaces

This book serves as an introduction to the flourishing field of super-resolution imaging. It is a compiled volume, with different authors for each of its 14 chapters. While not having a strong outline or textbook format, the chapters group into several sections.

Super-Resolution Imaging

Advances in ultrafast lasers, chirped pulse amplifiers, and frequency comb technology require fundamentally new pulse-modulation strategies capable of supporting unprecedentedly large bandwidth and high peak power while maintaining high spectral resolution. We demonstrate how dielectric metasurfaces can be leveraged to shape the temporal profile of a near-infrared femtosecond pulse. Finely tailored pulse-shaping operations, including splitting, compression, chirping, and higher-order distortion, are achieved using a Fourier-transform setup embedding metasurfaces able to manipulate, simultaneously and independently, the amplitude and phase of the constituent frequency components of the pulse. Exploiting metasurfaces to manipulate the temporal characteristics of light expands their impact and opens new vistas in the field of ultrafast science and technology.

/pdf/ultrafast-optical-pulse-shaping-using-dielectric-ryncbzq0gr.pdf

Ultrafast optical pulse shaping using dielectric metasurfaces

Shrinking conventional optical systems to chip-scale dimensions will benefit custom applications in imaging, displaying, sensing, spectroscopy, and metrology. Towards this goal, metasurfaces-planar arrays of subwavelength electromagnetic structures that collectively mimic the functionality of thicker conventional optical elements-have been exploited at frequencies ranging from the microwave range up to the visible range. Here, we demonstrate high-performance metasurface optical components that operate at ultraviolet wavelengths, including wavelengths down to the record-short deep ultraviolet range, and perform representative wavefront shaping functions, namely, high-numerical-aperture lensing, accelerating beam generation, and hologram projection. The constituent nanostructured elements of the metasurfaces are formed of hafnium oxide-a loss-less, high-refractive-index dielectric material deposited using low-temperature atomic layer deposition and patterned using high-aspect-ratio Damascene lithography. This study opens the way towards low-form factor, multifunctional ultraviolet nanophotonic platforms based on flat optical components, enabling diverse applications including lithography, imaging, spectroscopy, and quantum information processing.

/pdf/low-loss-metasurface-optics-down-to-the-deep-ultraviolet-1kkoyuzm1q.pdf

Low-loss metasurface optics down to the deep ultraviolet region

Low-loss Metasurface Optics down to the Deep Ultraviolet

New technologies are emerging that capture and redirect sunlight inside solar cells. This type of light management can significantly increase efficiency, but the device behavior will fundamentally depend on the spatial coherence of the incoming light. This dependence calls for a complete characterization of the spatial coherence of sunlight. Here, we present the first spectral measurements of the spatial degree of coherence of direct, diffuse, and simulated sunlight. An expression is derived for both the cross-spectral density and the spatial degree of coherence in an arbitrarily oriented device plane, including the effects of overcast skies. Implications of the present work are discussed and may lead to a better understanding of light-managing components in solar cells as well as a new class of solar simulator that provides both the same spectrum and spatial coherence as direct sunlight.

https://www.photonics.ethz.ch/fileadmin/user_upload/pdf/Papers/divitt15a.pdf

Spatial coherence of sunlight and its implications for light management in photovoltaics

We present an experimental method for the fast measurement of both the spectral (spatial) and complex degrees of coherence of an optical field using only a binary amplitude mask and a detector array. We test the method by measuring a two-dimensional spectral degree of coherence function created by a broadband thermal source. The results are compared to those expected by the van Cittert-Zernike theorem and found to agree well in both amplitude and phase.

https://www.photonics.ethz.ch/fileadmin/user_upload/pdf/Papers/divitt14a.pdf

Shawn Divitt

Papers

Ultrafast optical pulse shaping using dielectric metasurfaces

Low-loss metasurface optics down to the deep ultraviolet region

Low-loss Metasurface Optics down to the Deep Ultraviolet

Spatial coherence of sunlight and its implications for light management in photovoltaics

Measuring coherence functions using non-parallel double slits