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futurity_sci_tech 00892.txt

#Tiny optical tuning fork fits on a chip California Institute of technology rightoriginal Studyposted by Jessica Stoller-Conrad-Caltech on September 27 2013researchers have created an optical equivalent of a tuning fork that can help steady electronic currents needed to power high-end electronics and stabilize signals of high-quality lasers. Itâ#the first time such a device has been miniaturized to fit on a chip and may pave the way for improvements in high-speed communication navigation and remote sensing. hen you re tuning a piano a tuning fork gives a standardized pitch or reference sound frequency; in optical resonators the pitch corresponds to the color or wavelength of the lightsays Kerry Vahala professor of information science and technology and applied physics at the California Institute of technology (Caltech. ur device provides a consistent light frequency that improves both optical and electronic devices when it is used as a reference. good tuning fork controls the release of its acoustical energy ringing just one pitch at a particular sound frequency for a long timeâ##a sustaining property called the quality factor. For the study published in Nature Communications Vahala and his colleagues transferred this concept to their optical resonator focusing on the optical quality factor and other elements that affect frequency stability. The researchers were able to stabilize the light s frequency by developing a silica glass chip resonator with a specially designed path for the photons in the shape of what is called an Archimedean spiral. sing this shape allows the longest path in the smallest area on a chip. We knew that if we made the photons travel a longer path the whole device would become more stablesays Hansuek Lee a senior researcher in Vahala s lab and lead author on the paper. Frequency instability stems from energy surges within the optical resonatorâ##which are unavoidable due to the laws of thermodynamics. Because the new resonator has a longer path the energy changes are diluted so the power surges are dampenedâ##greatly improving the consistency and quality of the resonator s reference signal which in turn improves the quality of the electronic or optical device. In the new design photons are applied to an outer ring of the spiraled resonator with a tiny light-dispensing optic fiber; the photons subsequently travel around four interwoven Archimedean spirals ultimately closing the path after traveling more than a meter in an area about the size of a quarterâ##a journey 100 times longer than achieved in previous designs. In combination with the resonator a special guide for the light was used losing 100 times less energy than the average chip-based device. In addition to its use as a frequency reference for lasers a reference cavity could one day play a role equivalent to that of the ubiquitous quartz crystal in electronics. Most electronics systems use a device called an oscillator to provide power at very precise frequencies. In the past several years optical-based oscillatorsâ##which require optical reference cavitiesâ##have become better than electronic oscillators at delivering stable microwave and radio frequencies. While these optical oscillators are currently too large for use in small electronics there is an effort under way to miniaturize their key subcomponentsâ##like Vahala s chip-based reference cavity. miniaturized optical oscillator will represent a shift in the traditional roles of photonics and electronics. urrently electronics perform signal processing while photonics rule in transporting information from one place to another over fiber-optic cable. Eventually oscillators in high-performance electronics systems while outwardly appearing to be electronic devices will internally be purely opticalvahala says. he technology that Kerry and his group have introduced opens a new avenue to move precision optical frequency sources out of the lab and onto a compact robust and integrable silicon-based platformsays Scott Diddams physicist and project leader at the National Institute of Standards and Technology and a coauthor on the study. t opens up many new and unexplored options for building systems that could have greater impact to real-world applications. he project was in collaboration with Caltech startup company hqphotonics and received funding support from the Defense Advanced Research Projects Agency Caltech s Kavli Nanoscience Institute and the Institute for Quantum Information and Matter an NSF Physics Frontiers Center with support of the Gordon and Betty Moore Foundation. Source: California Institute of Technologyyou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license v

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