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of the process. EFT eliminates both these sources of failure. Devices made using EFT with proprietary passivation technology are exceptionally robust with respect to temperature and humidity, eliminating the need for costly hermetic packages.
Precision Facet Location: Device facets are formed with extreme precision, enabling low-cost passive alignment with silicon photonics.
“Active alignment of a light source to the silicon photonics chip is a costly process, requiring extremely expensive equipment,” comments Jonathan Klamkin, Director of the Integrated Photonics Laboratory at Boston University. “With EFT, BinOptics found a way to reap the cost and efficiency benefits of passive alignment without sacrificing the accuracy associated with real-time active alignment. This should be a critical factor for companies seeking economical, large-scale rollout of silicon photonics applications.”
“We needed an experienced but innovative InP partner who could provide a reliable, easy-to-integrate, non- hermetic light source for our silicon photonics platform,” concludes Mehdi Asghari, CTO, of Kotura. “BinOptics provided us with the fastest path to market for our new 100 Gbps optical engine, exceeding our expectations in every way.”
Harvesting energy from light in a new way
A new discovery could enhance optoelectronic devices and solar cell performance
Researchers from the University of Pennsylvania have demonstrated a new mechanism for extracting energy from light.
This could improve technologies for generating electricity from solar energy and lead to more efficient optoelectronic devices used in communications.
Dawn Bonnell, Penn’s vice provost for research and Trustee Professor of Materials Science and Engineering in the School of Engineering and Applied Science, led the work, along with David Conklin, a doctoral student.
“We’re excited to have found a process that is much more efficient than conventional photoconduction,” Bonnell comments. “Using such an approach could make solar energy harvesting and optoelectronic devices much better.”
The new work centres on plasmonic nanostructures, 92
www.compoundsemiconductor.net October 2013
specifically, materials fabricated from gold particles and light-sensitive molecules of porphyin, of precise sizes and arranged in specific patterns.
Plasmons, or a collective oscillation of electrons, can be excited in these systems by optical radiation and induce an electrical current that can move in a pattern determined by the size and layout of the gold particles, as well as the electrical properties of the surrounding environment.
Because these materials can enhance the scattering of light, they have the potential to be used to advantage in a range of technological applications, such as increasing absorption in solar cells.
Researchers fabricated nanostructures with various photoconduction properties
In 2010, Bonnell and colleagues published a paper in ACS Nano reporting the fabrication of a plasmonic nanostructure, which induced and projected an electrical current across molecules.
In some cases they designed the material, an array of gold nanoparticles, using a technique Bonnell’s group invented, known as ferroelectric nanolithography.
The discovery was potentially powerful, but the scientists couldn’t prove that the improved transduction of optical radiation to an electrical current was due to the “hot electrons” produced by the excited plasmons. Other possibilities included that the porphyin molecule itself was excited or that the electric field could focus the incoming light.
“We hypothesised that, when plasmons are excited to a high energy state, we should be able to harvest the electrons out of the material,” Bonnell explains. “If we could do that, we could use them for molecular electronics device applications, such as circuit components or solar energy extraction.”
To examine the mechanism of the plasmon-induced current, the researchers systematically varied the different components of the plasmonic nanostructure, changing the size of the gold nanoparticles, the size
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