Abstract of the invited speakers

 

Dr. Jos Benschop, ASML (NL)

EUV lithography: past, present and future

For more than 50 years the electronics industry has enabled a revolution in our daily life due to ever decreased feature sizes on our chips enabling faster, cheaper and more energy efficient computing and data storage. This trend is  commonly referred to as Moore’s Law.

To this day optical lithography has been the key enabler for Moore’s Law. It will be explained how a combination of increased Numerical Aperture and reduced wavelengths made this possible.

The latest step in wavelength has been a transition from 193nm ArF laser to 13.5 Extreme UltraViolet (EUV) plasma source. Results obtained with latest NA=0.33 EUV scanners will be shared. Finally status of next generation 0.55 numerical aperture EUV scanner will be shown.

 

Prof. Carl M. Bender, Washington University in St. Louis (USA)

Parity-Time (PT) Symmetry

By using complex-variable methods one can extend conventional Hermitian quantum theories into the complex domain. The result is a huge and exciting new class of parity-time-symmetric (PT-symmetric) theories whose remarkable physical properties are currently under intense study by theorists and experimentalists. Many theoretical predictions have been verified in recent beautiful laboratory experiments.

 

Prof. Larry Y-C Yauan, Shenzhen University (China)

Fast photonic histology imaging for interoperative pathology assessment

Histological analysis is the currently gold standard for surgical margin assessment, whereas a time-consuming preparation of histology slices precludes intraoperative histopathological interpretation of tumor margins during cancer surgery. Ultraviolet photoacoustic microscopy offers the same contrast label-freely as hematoxylin labeling in conventional histology examinations, which however fails to resolve the fine anatomic structures along the depth resolution because of poor axial resolution from the limited ultrasonic detection bandwidth. By exploiting ultrafast temporal dynamics and highly-localized evanescent field of optical surface wave, broadband response to photoacoustic impulses is accessed with high sensitivity, thus improving the depth resolution that is comparable with the standard histology slice thickness. Incorporating the novel sensor into ultraviolet photoacoustic microscope, three-dimensional histology imaging of cell nuclei is obtained in freshly-harvested tissues without sectioning and staining, allowing for fast, accurate intraoperative histopathology assessment for tumor resection surgeries.

 

Dr. Imran Avci, Vrije Universiteit Amsterdam (NL)

Photonic chips for diagnostic applications

Photonic chips are becoming more and more available in diagnostic applications such as biosensing and optical imaging. During this talk, I will walk you through these exciting applications and demonstrate how we make these chips in-house using a simple and fast technique.

 

Prof. G. Aeppli, EPFL (CH)

Phase retrieval in space and time using photons generated by electron accelerators

Over the last 50 years, electron accelerators, including both rings and linear machines, have exhibited an exponentially growing ability to deliver coherent photon beams of entirely variable wavelength. We show how this has already led to full three-dimensional lensless imaging of complex systems such as integrated circuits as well as to quantum state preparation in the time domain. New developments both for synchrotrons and free electron lasers promise dramatic future development of such capabalities.  

   

Prof. Tero Setälä, University of Eastern Finland (F)

Gram-matrix description of electromagnetic spatial coherence

We introduce a novel description of spatial coherence properties of random electromagnetic light beams in terms of the Gram matrix related to the cross-spectral density (CSD) matrix. This leads to the singular-value representation and Poincaré sphere visualization of (two-point) spatial coherence.

 

Dr. Armand Koolen, ASML (NL)

Ultrafast Modelling of Partial Coherent Fourier Scatterometry

In semiconductor device manufacturing, optical wafer metrology is a key technology for advanced control of the lithographic patterning in the multiple layers of an integrated circuit (IC). One such optical wafer metrology method is Fourier scatterometry, where the far-field diffraction pattern of periodic structures on the wafer is measured. In case of grating-on-grating wafer targets the lateral displacement, or overlay, between two IC layers can be measured using a technique called Diffraction-Based Overlay (DBO).
The complexity of signal formation in Fourier scatterometry under realistic conditions, i.e. in the context of optical sensor imperfections, depends a lot on the spatial coherence regime in which the Fourier scatterometer is operated. Only the fully coherent or fully incoherent limit allow for the use of fast 2D convolution models to predict the far-field patterns under such conditions. In the partial coherent regime, where the relative size between illuminated wafer spot and target is variable, 4D overlap integrals arise that do not allow for on-the-fly far-field predictions. In this talk we will present a perturbative technique, together with advanced analytical mathematics, that allows us to reduce the complexity of modelling partial coherent Fourier scatterometry to an ultrafast 2D convolution. The approach is fully vectorized and capable of predicting the impact of partial coherence and optical sensor properties on all Stokes parameters.

 

Prof. Sylvain Gigan,  Kastler-Brossel Laboratory, ENS Sorbonne, Paris (FR)

Fluorescence imaging in complex media: wavefront shaping and computational imaging

Light propagation in complex media can be coherently controlled, allowing focusing and imaging at depth. Fluorescence is an incoherent process, that is therefore not simply amenable to wavefront shaping technique. Yet linear fluorescence remains a staple tool in imaging and microscopy. 

I will discuss how non-invasive fluorescence imaging can be performed in scattering media, exploiting both wavefront shaping and computational tools such as phase-retrieval and non-negative matrix factorization techniques.

 

Prof. Ari Friberg, University of Eastern Finland (F) 

Phases of Vector Wave Beating

Interference of two vector fields of different frequencies, leading to a periodic superposition, allows the association of two kinds of phases, a geometric phase due to polarization changes and a dynamical phase due to field evolution. The geometric phase assumes a compact analytical expression in terms of the wave intensities and polarization states. It can also be obtained from the wave intensities and the interference fringe visibility. We have employed both approaches to demonstrate and confirm our results. The sum of the two phases is constant, implying that the dynamical phase depends on the polarization states of the two waves.

 

Prof. Martin Booth, University of Oxford (UK)

New dimensions for adaptive optics in microscopy

Adaptive optics (AO) is being widely adopted to correct phase aberrations introduced by microscope optical systems and specimens.  These aberrations compromise image quality by reducing contrast and resolution.  Adaptive elements, such as deformable mirrors or liquid crystal spatial light modulators, are used to modulate the optical wavefronts and remove aberrations.  Such AO systems have been developed for microscope applications ranging from deep-tissue imaging of neural activity to super-resolution microscopy.  However, AO can be applied to optical properties other than phase.  We will discuss developments in spatiotemporal control of short-pulse lasers and light polarization can further enhance the AO microscopy toolkit beyond solely phase correction.

 

Prof. D. Willingale, University of Leicester (UK)

Techniques and Technology for Diffraction Limited X-ray Imaging in Space

How can we design and manufacture mirrors, lenses and interferometers which can provide ultra-high angular resolution at the diffraction limit in X-ray telescopes? I will review the prospects of achieving diffraction limited X-ray imaging for astronomical observation in space.
 

Prof. Allard Mosk, University Utrecht (NL)

Spatial and spectral information in scattering media

The usefulness of adaptive wavefront shaping methods for focusing, imaging and metrology in scattering media has been demonstrated in many experiments and is making its way into applications. In very strongly scattering media, transport of energy and information takes place through a small number of open transport channels. The properties of these channels have come under intense scrutiny. We will show how measurements, simulations and random matrix theories reveal the spectral and spatial properties of the open transmission channels, and their strong dependence on the fraction of available information in the scattering matrix that we are able to access.

 

Dr. Zheng Xi, University of Science and Technology of China (China)

Metasurface for transverse displacement measurement

A long-range, high-precision and compact transverse displacement metrology method is of crucial importance in many research areas. In this talk, after briefly reviewing our previous work on nanoantennas for transverse displacement metrology, we will discuss our recent work on the polarization-encoded metasurface for sensitive long-range transverse displacement metrology. The transverse displacement of the metasurface is encoded into the polarization direction of the outgoing light via the Pancharatnam-Berry phase, which can be read out directlyaccording to the Malus law. We experimentally demonstrate nanometer displacement resolution with the sub-nanometer precision for a large measurement range of 200 mm.

 

 

Prof. Willem L. Vos, University of Twente, the Netherlands 

How to better confine photons with 3D silicon nanophotonics? Let’s go to the synchrotron to X-ray image our nanostructure

Three-dimensional (3D) nanostructures are receiving a fast-growing attention for their advanced functionalities in nanophotonics, photovoltaics, novel 3D integrated circuits, and flash memories. The functionality of such nanostructures is fundamentally determined by their complex internal structure. Since any fabricated nanostructure inevitably differs from design, the observed functionality differs from expectation. It is thus vital to assess the structure of a 3D nanomaterial with methods that keep the device fully functional and ready for further integration. Hence, we introduce traceless X-ray tomography (TXT) as a tool in nanotechnology to non-destructively assess the functionality of nanostructures, in particular in nanophotonics. 
Traditionally, a new nanostructures is inspected by scanning electron microscopy (SEM). A major limitation of SEM is that only the external surface is seen and the inside remains hidden. To inspect 3D structures, SEM is supplemented with ion beam milling to cut part of the structure away. Clearly, this approach is destructive and irreversible. Here we achieve nm resolution in structures on thick substrates using X-ray holographic tomography at the ESRF synchrotron with high photon energies. We study 3D photonic band gap crystals made from Si by CMOS-compatible means, as a prime example of 3D silicon nanophotonics. Such nanocrystals are powerful tools in cavity quantum electrodynamics (cQED) to control the quantum emission of light by their complete 3D photonic band gap. 
It appears that in nanophotonics, it is crucial where the involved quantum emitters (in our case: semiconductor quantum dots) are located inside the nanostructure, as this critically determines excited state lifetimes. Therefore, we have embarked on a project to control the positions of the quantum dots with advanced brush co-polymer surface chemistry. To find out where the quantum dots are located, we performed an X-ray fluorescence imaging tomography that will be elaborated. Strengths and limitations, and exciting future directions will be discussed.