System Bits: May 29
Photonic Building Blocks
For potential future use in applications such as tunable, metal-semiconductor devices for solar cells, sensors, solid-state lighting and chip-scale lasers along with digital cameras and advanced imaging systems, researchers from Stanford and the University of Pennsylvania have used ‘plasmonic cloaking’ to create a device that can see without being seen: an invisible machine that detects light.
This technology might even allow existing opto-electronic devices to be reengineered to incorporate new functions and to achieve sensor densities not possible today.
An image showing light scattering from a silicon nanowire running diagonally from bottom left to top right. The brighter areas are bare silicon while the dimmer sections are coated with gold demonstrating how plasmonic cloaking reduces light scattering in the gold-coated sections. (Source: Stanford University)
Inside the science, a coating of reflective metal can actually make something less visible, the engineers have shown in an invisible, light-detecting device that can see without being seen. At the heart of the device are silicon nanowires covered by a thin cap of gold. By adjusting the ratio of metal to silicon — a technique the engineers refer to as tuning the geometries — they capitalize on favorable nanoscale physics in which the reflected light from the two materials cancel each other to make the device invisible.
Quantum Dots Allow Ultra-Efficient Light Transmission
Capable of ultra-efficient transmission of light, researchers are edging toward the creation of new optical technologies using nanostructured metamaterials with potential applications including advanced solar cells, light emitting diodes and quantum information processing more powerful than today’s computers.
The metamaterial is composed of layers of silver and titanium oxide and tiny components called quantum dots that dramatically change the properties of light, which then becomes hyperbolic and increases the output of light from the quantum dots.
“Altering the topology of the surface by using metamaterials provides a fundamentally new route to manipulating light,” said Evgenii Narimanov, a Purdue University associate professor of electrical and computer engineering.
The work was a collaboration of researchers from Queens and City Colleges of City University of New York (CUNY), Purdue University, and University of Alberta. The experimental study was led by the CUNY team, while the theoretical work was carried out at Purdue and Alberta.
These metamaterials could make it possible to use single photons – the tiny particles that make up light – for switching and routing in future computers. While using photons would dramatically speed up computers and telecommunications, conventional photonic devices cannot be miniaturized because the wavelength of light is too large to fit in tiny components needed for ICs.
This graphic depicts a new "nanostructured metamaterial" - layers of silver and titanium oxide and tiny components called quantum dots - to dramatically change the properties of light. Researchers are working to perfect the metamaterials, which might be capable of ultra-efficient transmission of light, with potential applications including advanced solar cells and quantum computing. (Source: CUNY)
Nanostructured metamaterials could make it possible to reduce the size of photons and the wavelength of light, allowing the creation of new types of nanophotonic devices.
The researchers said these discoveries could help them develop quantum information systems far more powerful than today’s computers by taking advantages of a phenomenon described by quantum theory called entanglement: instead of only the states of one and zero, there are many possible entangled quantum states in between.
–Ann Steffora Mutschler
Tags: CUNY, nanostructured metamaterials, optoelectronics, photonic devices, plasmonic cloaking, Purdue University, Stanford University, University of Alberta, University of Pennsylvania