Department of Applied Physics and Materials Science - Applied Physics

News & Events

Highlights

Two Holograms in One Surface

12-11-17

Andrei Faraon, Assistant Professor of Applied Physics and Materials Science, graduate student Seyedeh Mahsa Kamali, and colleagues have figured out a way to encode more than one holographic image in a single surface without any loss of resolution. The team developed silicon oxide and aluminum surfaces studded with tens of millions of tiny silicon posts, each just hundreds of nanometers tall. Each nanopost reflects light differently due to variations in its shape and size, and based on the angle of incoming light. [Caltech story]

Tags: research highlights Andrei Faraon APh Seyedeh Mahsa Kamali

The Microscopic Origin of Efficiency Droop in LEDs

11-20-17

Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, and his colleagues’ semiconductor research has shown that the coupling between electrons and thermal vibrations may be sapping energy from Light-emitting diodes—or LEDs. "Our work shows for the first time that the ever-present interaction between electrons with lattice vibrations can, by itself, explain why excited electrons can leak out of the active layer and account for inefficiencies in GaN LEDs," Professor Bernardi says. [Caltech story]

Tags: APhMS research highlights Marco Bernardi

First On-chip Nanoscale Optical Quantum Memory Developed

09-11-17

Andrei Faraon, Assistant Professor of Applied Physics and Materials Science, and colleagues have developed a computer chip with nanoscale optical quantum memory. "Such a device is an essential component for the future development of optical quantum networks that could be used to transmit quantum information," says Professor Faraon (BS '04). [Caltech story]

Tags: research highlights Andrei Faraon APh

Reflective Nanostructures

07-13-17

Andrei Faraon, Assistant Professor of Applied Physics and Materials Science, and colleagues have discovered how to use computer-chip manufacturing technologies to create the kind of reflective materials that make safety vests, running shoes, and road signs appear shiny in the dark. The new technology uses surfaces covered by a metamaterial consisting of millions of silicon pillars, each only a few hundred nanometers tall. By adjusting the size of the pillars and the spacing between them, Faraon can manipulate how the surface reflects, refracts, or transmits light. [Caltech story]

Tags: APhMS research highlights Andrei Faraon

Grad Student Makes Ultra-Sensitive Measurement of Deformation

07-13-17

Xiaoyue Ni, a materials science graduate student working with Professor Julia Greer, has shown that metals undergo permanent deformation even prior to yielding—the threshold at which a material under strain becomes permanently deformed. "What Xiaoyue's data are showing is that from the first moment you start deforming it, the dislocations start being active," Greer says. Now that we know how to do this, we can probe a variety of different classes of materials. [Caltech story]

Tags: APhMS research highlights Julia Greer Xiaoyue Ni

Nanostructures Detect Colors

06-28-17

Harry Atwater, Howard Hughes Professor of Applied Physics and Materials Science; Director, Joint Center for Artificial Photosynthesis, and colleagues have combined nanophotonics and thermoelectrics to generate materials capable of distinguishing between tiny differences in wavelengths of light. [Caltech story]

Tags: APhMS research highlights Harry Atwater

A Rainbow of Possibilities

06-21-17

Professor Andrei Faraon, graduate student Ehsan Arbabi, and their colleagues have developed a metasurface or a sheet of material that can be altered on demand to exhibit properties not usually found in natural materials. For example, materials engineered at the nanoscale can control the dispersion of light and could be the basis of next-generation spectrometers and other imaging devices. [Caltech story]

Tags: APhMS research highlights Andrei Faraon Ehsan Arbabi

2017 Library Thesis Prize

06-20-17

Senior Daniel Lim has received the 2017 Library Friends' Senior Thesis Prize for his work on sculpting nanofilms with laser illumination. Lim's thesis, titled "Revolution in large-area curved surface lithography: Nanofilm sculpting by thermocapillary modulation," is based on experimental research he conducted over two years in the laboratory of Professor of Applied Physics, Aeronautics, and Mechanical Engineering Sandra M. Troian. "Our group has been working on thermocapillary sculpting of nanofilms for several years now,” says Troian. "Daniel advanced this concept by demonstrating an inverse projection method, which imbues the sculpting process with far greater versatility. Daniel is an exceptional student—a rare combination of superb talent, tremendous drive, utmost professionalism, and entrepreneurial chops. " [Caltech story]

Tags: APhMS honors research highlights MCE Sandra Troian Daniel Lim

"Hot" Electrons Move Faster Than Expected

06-15-17

For the first time, Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, and colleagues have been able to directly observe the ultrafast motion of electrons immediately after they are excited with a laser—and found that these electrons diffuse into their surroundings much faster and farther than previously expected. "Our work shows the existence of a fast transient that lasts for a few hundred picoseconds, during which electrons move much faster than their room-temperature speed, implying that they can cover longer distances in a given time when manipulated with lasers," says Professor Bernardi. "This non-equilibrium behavior could be employed in novel electronic, optoelectronic, and renewable energy devices, as well as to uncover new fundamental physics." [Caltech story]

Tags: APhMS research highlights Marco Bernardi

Observations Reshape Basic Plasma Wave Physics

04-06-17

Paul M. Bellan, Professor of Applied Physics , and colleagues have discovered a new way to determine the wavelength of energy flowing through plasma in space—a method that was recently applied during a NASA mission that yielded the first solid evidence of how energy sloshes back and forth in a magnetic wave that moves through the plasma surrounding the earth. [Caltech story]

Tags: APhMS research highlights Paul Bellan