Department of Applied Physics and Materials Science - Applied Physics

News & Events


Levitating Objects with Light


Ognjen Ilic, postdoctoral scholar in Professor Harry Atwater’s laboratory, and colleagues have designed a way to levitate and propel objects using only light, by creating specific nanoscale patterning on the objects' surfaces. "We have come up with a method that could levitate macroscopic objects," says Professor Atwater, who is also the director of the Joint Center for Artificial Photosynthesis. "There is an audaciously interesting application to use this technique as a means for propulsion of a new generation of spacecraft. We're a long way from actually doing that, but we are in the process of testing out the principles." [Caltech story]

Tags: APhMS research highlights Harry Atwater postdocs Ognjen Ilic

New Materials Exhibit Split Personality


Julia Greer, Professor of Materials Science, Mechanics and Medical Engineering, and colleagues have determined that the failure of architected materials—the point at which they break when compressed or stretched—can be described using classical continuum mechanics, which models the behavior of a material as a continuous mass rather than as individual (or "discrete") particles. This finding implies a duality to the nature of these materials—in that they can be thought of both as individual particles and also as a single collective. [Caltech story]

Tags: APhMS research highlights MCE Julia Greer

Microscopic Devices That Control Vibrations Could Allow Smaller Mobile Devices


Chiara Daraio, Professor of Mechanical Engineering and Applied Physics, and colleagues have developed phononic devices that include parts that vibrate extremely fast, moving back and forth up to tens of millions of times per second. The devices were developed by creating silicon nitride drums that are just 90 nanometers thick. The drums are arranged into grids, with different grid patterns having different properties. Professor Daraio, along with former Caltech postdoctoral scholar Jinwoong Cha, have shown that arrays of these drums can act as tunable filters for signals of different frequencies and can act like one-way valves for high-frequency waves. [Caltech story]

Tags: research highlights Chiara Daraio MCE APh postdocs Jinwoong Cha

"Folded" Optical Devices Manipulate Light in a New Way


Andrei Faraon, Professor of Applied Physics, and colleagues have introduced a technology called "folded metasurface optics," which is a way of printing multiple types of metasurfaces onto either side of a substrate, like glass. In this way, the substrate itself becomes the propagation space for the light. As a proof of concept, the team used the technique to build a spectrometer. Such compact spectrometers have a variety of possible uses, including as a noninvasive blood-glucose measuring system. [Caltech story]

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Caltech Startup Aims to Make Solar Panels More Efficient


Translational technology developed in Professor Harry A. Atwater’s laboratory seeks to improve the efficiency of solar panels by tweaking the architecture of the metal-grid layout of individual cells. The new startup company—ETC Solar, LLC—which is marketing the technology, took first place at the DOE's 2018 Cleantech University Prize national collegiate business plan competition in Houston. "To have been selected as a winner is a huge point of validation for the concept, both the innovation and also the impact," says Professor Atwater, who is also a co-founder of ETC Solar along with Thomas Russell, and Rebecca Saive. "It has helped us to make contacts with potential industrial partners and private equity investors," [Caltech story]

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Caltech Awarded Federal Funding for Quantum Research


EAS Professors were among a small group of Caltech scientists and engineering who have won federal grants for research in quantum computing, and quantum networks. Professor Nadj-Perge (lead PI) along with co-PIs Professors Marco Bernardi and Andrei Faraon as well as co-investigator Professor Julia Greer have received funding for the program ”Quantum States in Layered Heterostructures Controlled by Electrostatic Fields and Strain," which is administered within the U.S. Department of Energy's Basic Energy Sciences division. Professor Austin Minnich is a co-PI of the program, "Quantum simulation of materials and molecules using quantum computation," which is part of the National Science Foundation's Research Advanced by Interdisciplinary Science and Engineering (RAISE)-Transformational Advances in Quantum Systems (TAQS) effort. [Caltech story]

Tags: APhMS research highlights MCE Julia Greer Austin Minnich Andrei Faraon Marco Bernardi Stevan Nadj-Perge

Clues to Solar Cell Efficiency Found at Atomic Level


Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, has teamed up with physics colleague Professor David Hsieh, to offers new insight into a promising solar cell material called perovskites. "Despite being a relatively new technology, perovskite solar cells are now almost as efficient as solar cell materials that have been around for decades. But we still don't know why perovskite solar cells work so well," says Professor Bernardi, [Caltech story]

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Exact Optical Frequencies on Demand


Professor Kerry J. Vahala and colleagues have developed a prototype of a miniature device that synthesizes frequencies on demand with about 1 Hertz accuracy. It combines a frequency comb developed at the National Institute of Standards and Technology (NIST) with a "fine-toothed" frequency comb developed at Caltech. To create the finely spaced comb teeth, the Caltech resonator must be about 100 times larger than the NIST device. Its larger size can potentially make this comb very power hungry. "Too much power in a small space can damage any electronics to which the resonator is connected," Professor Vahala says. "Also, in the future, these synthesizer devices could operate on battery power in smartphone-sized devices where they cannot draw much power." But the Caltech comb can generate specific frequencies with minimal amounts of power. [Caltech story]

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Building the Starshot Sail


Professor Harry A. Atwater, Jr. is an advisor to a multi-disciplinary $100-million project aimed at designing a spacecraft that can be launched to planets surrounding other stars and reach them within our lifetime. The Breakthrough Starshot Program has three big technical challenges: The first is to build the so-called photon engine, the laser that's capable of propelling the sail; the second is to design the sail itself; and the third is to design the payload, which will be a tiny spacecraft capable of taking images and spectral data and then beaming them back to the earth. Professor Atwater’s role is to help the program define pathways to making a viable lightsail that's compatible with the other objectives of the whole program. [Caltech story]

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Quantum and non-linear forces yield peculiar thermal expansion in silicon


Most materials expand when heated. At temperatures below room temperature, silicon shows the opposite behavior, shrinking as it is heated. Even at room temperature the normal thermal expansion of silicon is rather small. A team led by Professor Brent Fultz wanted to know why, and found that the unusual property is the result of quantum effects coupled by the nonlinear forces between atoms in silicon. [Read the paper]

Tags: APhMS research highlights Brent Fultz Dennis Kim