The work marks the first time that such a device has been miniaturized to fit on a chip and may pave the way to improvements in high-speed communications, navigation, and remote sensing.
A photograph of the spiral chip-based optical resonator developed at Caltech, shown next to a quarter to provide scale. Credit: Hansuek Lee/Caltech
"When 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 light. Our device provides a consistent light frequency that improves both optical and electronic devices when it is used as a reference," says Kerry Vahala, Ted and Ginger Jenkins Professor of Information Science and Technology and Applied Physics. Vahala is also executive officer for applied physics and materials science and an author on the study describing this new work, published in the journal Nature Communications.
A good tuning fork controls the release of its acoustical energy, ringing just one pitch at a particular sound frequency for a long time; this sustaining property is called the quality factor. 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. "Using 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 stable," says Hansuek Lee, a senior researcher in Vahala's lab and lead author on the paper.
Frequency instability stems from energy surges within the optical resonator—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 dampened—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 quarter—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 oscillators—which require optical reference cavities—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 subcomponents—like Vahala's chip-based reference cavity.
"A miniaturized optical oscillator will represent a shift in the traditional roles of photonics and electronics. Currently, 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 optical," Vahala says.
"The 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 platform," says Scott Diddams, physicist and project leader at the National Institute of Standards and Technology, recent Moore Distinguished Scholar at Caltech and a coauthor on the study. "It opens up many new and unexplored options for building systems that could have greater impact to 'real-world' applications," Diddams says.
The paper, titled "Spiral resonators for on-chip laser frequency stabilization," was published online in Nature Communications on September 17. Other Caltech coauthors on the study include graduate students Myoung Gyun Suh and Tong Chen (PhD '13), and postdoctoral scholar Jiang Li (PhD '13). The project was in collaboration with Caltech startup company hQphotonics. This work was funded by the Defense Advanced Research Projects Agency; the 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.
Written by Jessica Stoller-ConradContact:
Deborah Williams-Hedges | EurekAlert!
Data use draining your battery? Tiny device to speed up memory while also saving power
14.12.2018 | Purdue University
Studying how unconventional metals behave, with an eye on high-temperature superconductors
13.12.2018 | Princeton University
The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.
Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...
What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...
12.12.2018 | Event News
10.12.2018 | Event News
06.12.2018 | Event News
14.12.2018 | Power and Electrical Engineering
14.12.2018 | Physics and Astronomy
14.12.2018 | Physics and Astronomy