06/28/2017 12:43:36
Robert Perkins
Engineers create nanoscale light detectors capable of distinguishing between different colors.
Color detectors
Thursday, August 24, 2017
Center for Student Services 360 (Workshop Space) – Center for Student Services

CTLO's 2nd Annual Summer Short Course for Faculty: (Re)Designing Your Class

06/20/2017 17:30:30
Lori Dajose
Senior Daniel Lim has received the 2017 Library Friends' Senior Thesis Prize for his work on sculpting nanofilms with laser illumination.
Soon Wei Daniel Lim
06/21/2017 09:54:35
Robert Perkins
Engineers have built a camera that does not need lenses to focus light.
The OPA chip placed on a penny for scale

A Rainbow of Possibilities

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A Rainbow of Possibilities
 An artist's representation of how a metasurface composed of nanoposts disperses light.
Credit: Ella Maru Studio

An artist's representation of how a metasurface disperses light. This metasurface—a sheet of material that can be altered on demand to exhibit properties not usually found in natural materials—was developed by Caltech's Andrei Faraon, assistant professor of applied physics and materials science; graduate student Ehsan Arbabi; and their colleagues from the Faraon lab.

When white light passes through a prism, various wavelengths are spread out, creating phenomena like the rainbow we see after a rain. Optical components known as diffraction gratings take advantage of this by using patterns in the spectra of light reflected off an object to provide information about that object's chemical makeup. Such diffraction gratings are commonly found in spectrometers.

A diagram showing how different types of lenses diffract light.
Credit: Andrei Faraon/Caltech

Just as lenses can be shaped to control how they bend light, Faraon and Arbabi demonstrated that their metasurfaces composed of nanoscale silicon pillars can be designed to perform the same task.

In a recent article published in the journal Optica, the engineers showed that the size and arrangement of these pillars can be used to control the dispersion of diffraction gratings, allowing light to be spread out over a broader range of angles or even to flip the order of the colors. 

A scanning electron microscope image of the silicon nanopillars forming a metasurface.
Credit: Andrei Faraon/Caltech

A scanning electron microscope image of the silicon nanopillars forming a metasurface, each smaller than the wavelength of light.  The team arranged them in patterns that diffract light in specific ways. This technique could be used to create future generations of spectrometers.

This discovery may yield improved performance of optical devices in applications like lasers and imaging. Faraon and Arbabi collaborated on this research with Caltech graduate students Seyedeh Mahsa Kamali, Yu Horie, and researcher Amir Arbabi. This research was funded by Samsung Electronics, the National Science Foundation, the Department of Energy, and the Defense Advanced Research Projects Agency. 


Materials engineered at the nanoscale can control the dispersion of light and could be the basis of next-generation spectrometers and other imaging devices.

Exclude from Caltech Today: 
Wednesday, June 28, 2017
Noyes 147 (J. Holmes Sturdivant Lecture Hall) – Arthur Amos Noyes Laboratory of Chemical Physics

Teaching Statement Workshop

06/19/2017 10:08:26
Lori Dajose
Caltech's 123rd annual commencement
photo of Mae Jemison speaking at Caltech's 2017 Commencement
06/15/2017 16:19:39
Lori Dajose
Underrepresented minority postdoctoral scholars discuss their experiences with the AGEP program at Caltech.
06/15/2017 14:51:53
Break Through, publicly launched just over a year ago, is already the most successful campaign in Caltech’s history.
photo of Ruthwick and Sathwick Pathireddy
06/15/2017 12:24:43
Robert Perkins
Electrons excited by a laser diffuse through a material 1,000 times faster than their room-temperature counterparts, study shows.