Controlling Light with a Material Three Atoms Thick
10-22-21
Scientists can control light more precisely than ever with a material only three atoms thick and constructed from so-called black phosphorous. In the lab of Harry Atwater, Otis Booth Leadership Chair, Division of Engineering and Applied Science; Howard Hughes Professor of Applied Physics and Materials Science; Director, Liquid Sunlight Alliance, three layers of phosphorous atoms were used to create a material for polarizing light that is tunable, precise, and extremely thin. Black phosphorous tech could revolutionize telecommunications by vastly improving light signals sent through fiber-optic cables. The technology could also open the door to a light-based replacement for Wi-Fi, something researchers in the field refer to as Li-Fi. "Increasingly, we're going to be looking at light-wave communications in free space," Atwater says. "Lighting like this very cool-looking lamp above my desk doesn't carry any communication signal. It just provides light. But there's no reason that you couldn't sit in a future Starbucks and have your laptop taking a light signal for its wireless communication rather than a radio signal. It's not quite here yet, but when it gets here, it will be at least a hundred times faster than Wi-Fi." [Caltech story]
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Harry Atwater
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Nano-Architected Material Resists Impact Better Than Kevlar
06-25-21
Julia R. Greer, Ruben F. and Donna Mettler Professor of Materials Science, Mechanics and Medical Engineering; Fletcher Jones Foundation Director of the Kavli Nanoscience Institute, has developed a nano-architected material made from tiny carbon struts that is, pound for pound, more effective at stopping a projectile than Kevlar, a material commonly used in personal protective gear. "The knowledge from this work could provide design principles for ultra-lightweight impact resistant materials for use in efficient armor materials, protective coatings, and blast-resistant shields desirable in defense and space applications," says Greer. [Caltech story]
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Julia Greer
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New Insight into Nonlinear Optical Resonators Unlocks Door to Numerous Potential Applications
02-25-21
Devices known as optical parametric oscillators are among the widely used nonlinear resonators in optics; they are "nonlinear" in that there is light flowing into the system and light leaking out, but not at the same wavelengths. Though these oscillators are useful in a variety of applications, including in quantum optics experiments, the physics that underpins how their output wavelength, or spectrum, behaves is not well understood. "When you add strong nonlinearity to resonators, you enter what we call a 'rich physics regime,'" says Alireza Marandi, Assistant Professor of Electrical Engineering and Applied Physics. "'Rich' in physics terms usually means complicated and hard to use, but we need nonlinearities to create useful functionalities such as switching for computing." To be able to make full use of nonlinear optical resonators, researchers want to be able to understand and model the physics that underpin how they work. Marandi and his colleagues recently uncovered a potential way to engineer those rich physics, while discovering phase transitions in the light that is generated by the resonators. [Caltech story]
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Alireza Marandi
Caltech and NTT Research Launch Collaboration to Develop World’s Fastest Coherent Ising Machine
01-25-21
Researchers from Caltech and NTT Research are collaborating to develop a high-speed Coherent Ising Machine (CIM). A CIM is a network of optical parametric oscillators (OPOs) programmed to solve problems that have been mapped to an Ising model, which is a mathematical abstraction of magnetic systems composed of competitively interacting spins, or angular momentums of fundamental particles. The principal investigator at Caltech for this four-and-a-half-year joint project is Kerry Vahala, Ted and Ginger Jenkins Professor of Information Science and Technology and Applied Physics; Executive Officer for Applied Physics and Materials Science. “We are delighted at the prospect of working with Professor Vahala to develop an extremely small and high-speed CIM,” said NTT Research PHI Lab Director, Yoshihisa Yamamoto. “This work will advance our understanding of the CIM’s capabilities, map well with ongoing and related work with other institutions, provide new demonstrations of this awesomely powerful new information system and, we hope, set standards for the CIM’s speed and size.” [NTT Research story] [Business Wire story]
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Kerry Vahala
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A Method to Map Brain Circuits in Real Time
10-16-20
A new approach called integrated neurophotonics could allow researchers to track the activity of all the neurons that make up a particular brain circuit. To deepen their understanding of the brain, neuroscientists must be able to map in great detail the neural circuits that are responsible for tasks such as processing sensory information or forming new memories. Now, a new approach may allow for the activity of all of the thousands to millions of neurons within a particular brain circuit to be observed in real time. Dense recording at depth—that is the key," says Michael Roukes, Frank J. Roshek Professor of Physics, Applied Physics, and Bioengineering. [Caltech story]
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Michael Roukes
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New Device Powers Wearable Sensors Through Human Motion
10-16-20
Wei Gao, Assistant Professor of Medical Engineering, has been developing sensors as well as novel approaches to power them. Previously, he created a sensor that could monitor health indicators in human sweat that is powered by sweat itself. Now, Gao has developed a new way to power wireless wearable sensors: He harvests kinetic energy that is produced by a person as they move around. "Instead of using fancy materials, we use commercially available flexible circuit boards," he says. "This material is cheap and very durable and mechanically robust over long periods of time." [Caltech story]
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Wei Gao
Professor Gao Unveils Sensor that Rapidly Detects COVID-19 Infection Status, Severity, and Immunity
10-02-20
One feature of the COVID-19 virus that makes it so difficult to contain is that it can be easily spread to others by a person who has yet to show any signs of infection. Wei Gao, Assistant Professor of Medical Engineering, has developed a new type of multiplexed test (a test that combines multiple kinds of data) with a low-cost sensor that may enable the at-home diagnosis of a COVID infection through rapid analysis of small volumes of saliva or blood, without the involvement of a medical professional, in less than 10 minutes. "This is the only telemedicine platform I've seen that can give information about the infection in three types of data with a single sensor," Gao says. "In as little as a few minutes, we can simultaneously check these levels, so we get a full picture about the infection, including early infection, immunity, and severity." [Caltech story]
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Wei Gao