Publications related to Gradient-index optics

Laser-based manufacturing of freeform glass micro-optics through topological transformation

Glass has been the material of choice for making optical elements, in large part due to its intrinsic properties: a temperature-dependent viscosity, which enables shaping the material into a broad variety of functional and artistic glassware. Silica glass ...

EPFL2024

Femtosecond laser-induced modifications and self-organization in complex glass systems

Gözden Torun

Ultrashort laser pulses, i.e., pulses emitted shorter than a picosecond, can tailor material properties by introducing permanent modifications locally in three dimensions. Remarkably, under a certain exposure condition, these modifications are accompanied ...

EPFL2023

Space-time wave packets with reduced divergence and tunable group velocity generated in free space after multi-mode fiber propagation

Tobias Kippenberg, Maxim Karpov, Hao Song, Xinzhou Su

Previously, space-time wave packets (STWPs) have been gen-erated in free space with reduced diffraction and a tunable group velocity by combining multiple frequency comb lines each carrying a single Bessel mode with a unique wave num-ber. It might be poten ...

Optica Publishing Group2023

Exploring Novel Modalities for Optical Diffraction Tomography

Amirhossein Saba Shirvan

In the past decade, optical diffraction tomography has gained a lot of attention for its ability to create label-free three-dimensional (3D) images of the refractive index distribution of biological samples using scattered fields measured through holograph ...

EPFL2023

van der Waals Materials for Overcoming Fundamental Limitations in Photonic Integrated Circuitry

Arslan Mazitov

With the advance of on-chip nanophotonics, there is a high demand for high-refractive-index and low-loss materials. Currently, this technology is dominated by silicon, but van der Waals (vdW) materials with a high refractive index can offer a very advanced ...

AMER CHEMICAL SOC2023

Active Ferromagnetic Metasurface with Topologically Protected Spin Texture for Spectral Filters

Dirk Grundler, Haiming Yu, Jilei Chen

Electromagnetic metasurfaces modulate a material's response to electromagnetic waves by specifically arranged elements with dimensions below the wavelength. They have opened new fields of research, including flat optics and nanophotonics on a chip. Ferroma ...

2022

Optical metasurfaces: synthesis, nanofabrication, and colorful applications

Hsiang-Chu Wang

In this thesis, we mainly utilize silver to construct the meta-atoms. Although suffering from easily oxidized, its excellent lossless property throughout the visible range makes it suitable for study. When preserved properly, silver-made metasurfaces can s ...

EPFL2022

Analysis of uncoated LPGs written in B-Ge doped fiber under proton irradiation for sensing applications at CERN

Tiago Filipe Pimentel Das Neves

In this contribution, a complete dissertation concerning the behavior of a Long Period Grating (LPG) inscribed in a B-Ge co-doped optical fiber by means of an excimer laser and exposed to proton irradiation during a recent extensive campaign performed at t ...

Nature Research2020

Lower Hybrid Current Drive in High Aspect Ratio Tokamaks

Hoang-Trang Lam, Joan Decker, Xiaoxia Bai

A multi-machine study has been carried out to investigate the impact of a strongly bounded wave propagation domain on the Lower Hybrid current drive, a condition which occurs principally in high aspect ratio tokamaks. In this regime, the condition of kinet ...

SPRINGER2020

Fiber-interface directional coupler inscribed by femtosecond laser for refractive index measurements

Jiangtao Zhou, Zhechen Zhang, Yiping Wang, Jiachen Wang

A novel fiber-interface directional waveguide coupler was inscribed on the surface of a coreless fiber by femtosecond laser, and was successfully applied to highly sensitive refractive index (RI) measurements. The primary arm was first inscribed to couple ...

2020

Ultrasensitive hyperspectral imaging and biodetection enabled by dielectric metasurfaces

Volkan Cevher, Hatice Altug, Filiz Yesilköy, Andreas Tittl, Yasaman Jahani, Eduardo Romero Arvelo, Mingkai Liu

Metasurfaces based on resonant subwavelength photonic structures enable novel ways of wavefront control and light focusing, underpinning a new generation of flat-optics devices. Recently emerged all-dielectric asymmetric metasurfaces, composed of arrays of ...

Nature Publishing Group2019

Gain enhancement of circular waveguide antennas using near-zero index metamaterials

Kosmas Tsakmakidis, Ershad Mohammadi, Foziyeh Sohrabi

In this article, a rigorous analytical methodology is introduced for designing near-zero refractive index metamaterials (NZIMs). Our proposed NZIM media is realized by three stacked layers of perforated metallic surfaces, each layer composed of a fishnet-l ...

WILEY2019

Mitsuba 2: A Retargetable Forward and Inverse Renderer

Wenzel Alban Jakob, Tizian Lucien Zeltner, Delio Aleardo Vicini, Merlin Eléazar Nimier-David

Modern rendering systems are confronted with a dauntingly large and growing set of requirements: in their pursuit of realism, physically based techniques must increasingly account for intricate properties of light, such as its spectral composition or polar ...

ASSOC COMPUTING MACHINERY2019

Design and implementation of quasi-optical components for the upgrade of the TCV EC-system

Timothy Goodman, Stefano Alberti, Jean-Philippe Hogge, Laurie Porte, Matthieu Toussaint, Florian Ramseyer

The EC-system of the TCV tokamak is progressively being upgraded with the addition of two MW-class dual-frequency gyrotrons (84 and 126 GHz/2s/1MW). In order to connect the two gyrotrons to the existing low field side and top launchers, new waveguide routi ...

ELSEVIER SCIENCE SA2019

Leveraging wafer-level manufacturing process limitations to increase large scale fused silica microlens array uniformity

Toralf Scharf, Wilfried Noell, Raoul Kirner, Jeremy Béguelin

The wafer-level production of Fused Silica microlens arrays is limited by systematic process non-uniformities. The common molten resist-reflow process with subsequent dry-etching allows for manufacturing of microlens arrays on 200 mm wafers. A thorough pro ...

SPIE-INT SOC OPTICAL ENGINEERING2019

Integrated Gallium Phosphide Photonics

Katharina Schmeing

The integration of new materials mediating light-matter interaction in nanoscale devices is a persistent goal in nanophotonics. One of these materials is Gallium phosphide, which offers an attractive combination of a high refractive index (n=3.05 at a wave ...

EPFL2019

Two-photon imaging and selective laser ablation of Cochlea hair cells through a multimode fiber probe

Demetri Psaltis, Christophe Moser, Damien Claude-Marie Loterie, Eirini Kakkava, Marilisa Romito

We demonstrate multimode fiber probe that accomodates dual modality properties for high power ultrashort pulse delivery. A commercially available multimode graded-index (GRIN) fiber is used for two-photon imaging and/or femtosecond laser ablation of Cochle ...

SPIE-INT SOC OPTICAL ENGINEERING2019

Stepwise Luneburg Lens for Bloch Surface Waves

Myun Sik Kim, Babak Vosoughi Lahijani

In order to enlarge the capability for in-plane manipulation of the Bloch surface wave (BSW), we investigate 2D gradient index (GRIN) optical components using a finite-difference time-domain (FDTD) numerical method. To ease difficulties in fabrication to a ...

2018

Tomographic imaging with harmonic holography in tissues of known refractive index distribution

Demetri Psaltis, Ye Pu

High-resolution imaging in thick biological tissues beyond a few transport mean free path of photons remains a formidable challenge to modern science and technology. Recent advancements in optical tomography have enabled the reconstruction of the three-dim ...

SPIE-INT SOC OPTICAL ENGINEERING2018

Wavefront shaping for ultrashort pulse delivery through optical fibers for imaging and ablation

Demetri Psaltis, Christophe Moser, Damien Claude-Marie Loterie, Eirini Kakkava, Nicolino Stasio, Donald Benjaman Conkey

We demonstrate high power ultrashort pulse delivery through a commercially available multicore fiber (MCF) and a multimode graded-index fiber (GRINF) for imaging and laser ablation. Lensless focusing and digital scanning of ultrashort pulses through the op ...

SPIE-INT SOC OPTICAL ENGINEERING2018