New device may lead to better electronics

Researchers have developed a new 'tuning fork' like device that can help steady the electrical currents needed to power high-end electronics and stabilise the signals of high-quality lasers.
The work marks the first time that such a device has been miniaturised to fit on a chip and may pave way to improvements in high-speed communications, navigation, and remote sensing, researchers said.
"Our device provides a consistent light frequency that improves both optical and electronic devices when it is used as a reference," said Kerry Vahala, Professor of Information Science and Technology and Applied Physics.
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 stabilise 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," said 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 spiralled resonator with a tiny light-dispensing optic fibre.
The photons subsequently travel around four interwoven Archimedean spirals, ultimately closing the path after travelling 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.
The study was published in the journal Nature Communications.