News

Adapted polarization camera

Turning any camera into a polarization camera

March 8, 2022

In recent work, we have shown that a suitably-designed polarization-sensitive metasurface grating when paired with a conventional imaging system can serve as an "attachment" rendering it capable of polarization imaging. We describe the design rules that govern this process, and show as an example the adaptation of a simple machine vision camera with a metasurface grating.

More broadly, the work serves as a guide to using metasurface polarization gratings in optical systems more generally. These may be used as a polarization-sensitive component in a wide variety of contexts,...

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Laser frequency comb

Fast gain recovery lasers on the cover of Laser and Photonics Reviews

February 9, 2022

The peculiar physics of quantum cascade lasers has led to the discovery of new frequency comb phenomena beyond traditional ones such as harmonic states, characterized by mode skipping, time-dependent spatial hole burning, turbulent states, recently observed in ring cavities, just to mention a few. These new types of frequency combs open technological and fundamental perspectives, such as laser radio applications and deep connections with passive Kerr microresonators, which are the object of our review.

See the publication on Laser and Photonics Reviews...

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Ahmed_TAM_plates

Structuring optical vortices in 3D

November 18, 2021

Optical vortices —light structures which look like donuts and can rotate around their axis of propagation— have attracted wide interest as new means for free space communications, optical trapping, and structured illumination in microscopes. Current wavefront shaping methods, however, can only provide limited control over the vorticity and the polarization (photon’s spin) of those beams in 3D space, thus limiting their application. In this study, we introduce a new type of metasurfaces which can generate complex optical vortices in which both the vortex strength and polarization state...

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Metasurface pulse compressor

Silicon nanocoatings make ultrafast pulses ultrafaster

November 12, 2021

Transparent bulk optical components have an unfortunate tendency to stretch out ultrashort laser pulses upon transmission. This effect – also known as group delay dispersion – destroys the carefully designed time-structure of the affected pulses. In this study, we show that precisely shaped silicon nanopillars can achieve the opposite effect, compressing the laser pulses and compensating for the dispersion of other optical elements. The technology is ready to be coated onto abundantly available standard optics to allow their application in the future of ultrafaster femtosecond optics....

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EOSLM

Electro-optic spatial light modulator from a single organic layer

October 14, 2021

Spatial light modulators (SLM) provide tailored light fields for many applications. Here, we show that an SLM device can be realized from a structure as simple as a single organic electro-optic material deposited on top of interlaced gold electrodes. When we apply an electric signal across these electrodes, the refractive index of the electro-optical film changes. By nanoscale engineering of the nonlinear properties of the material and electrodes, we demonstrate modulation of the intensity of light at speeds up to 50 MHz, with tiny microwatt-level switching electrical...

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A high aspect ratio holey metalens

A high aspect ratio holey metalens

October 13, 2021

Multiple beneficial optical device properties scale with the thickness of nanostructures. For example, taller nanostructures afford a greater degree of control over multiple colors of light, expanding the range of chromatic behaviors and possibly leading to large-area achromatic metalenses. However, in conventional meta-optics, which employ free-standing nanopillars or nanofins, increasing the nanostructure height while maintaining subwavelength nanostructure spacing requires high aspect ratio structures (aspect ratio = height to width ratio), which are difficult to fabricate and work...

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Metasurfaces control polarized light at-will

August 16, 2021

In recent years, considerable attention has been paid to the ability of metasurface optics to manipulate polarized light. A variety of works and applications have been demonstrated showing, for instance, how metasurfaces can create optics with different behaviors that switch on the basis of light's polarization state, or that produce polarized holograms.

In recent work published in Science Advances, we show that a new perspective - which we dub "Jones matrix holography" - generalizes much of this past work and suggests new possibilties as well that exceed the level of...

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One metasurface to rule them all

One metasurface to rule them all

July 12, 2021

It typically takes several independently-controlled components to fully manipulate the various degrees of freedom (e.g. wavelength, shape, and power) of a laser beam. In this publication, we show that a single reflective metasurface and a laser diode can exert full control of the shape and intensity of diffraction orders. The design does not require any rotating components and is compact. The research has applications in quantum sensing and virtual reality/augmented reality (VR/AR) headsets. 

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heart shaped phase singularity

Harnessing the dark side with optical singularities

July 12, 2021

Do black holes come to mind when you think about singularities? In optics, singularities occur when one or more parameters are undefined, and are also associated with non-intuitive phenomena such as energy backflow and superoscillations. While the vast majority of optical singularities take the form of string-like lines and loops, this paper introduces a technique to engineer singularities belonging to a wider class of shapes. As a demonstration, the authors engineer sheet singularities that have heart-shaped cross-sections, then realize these light fields experimentally using...

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