Researchers at the California Institute of Technology (Caltech) have developed an optical “tuning fork” device they say could help improve high-speed communications, navigation and remote sensing by stabilizing the signals of high-quality lasers and the electrical currents needed to power electronics.
“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,” Kerry Vahala, Ted and the Ginger Jenkins Professor of information science and technology and applied physics, said. A silica glass chip resonator with a specially designed path for the photons in the shape of an Archimedean spiral was used to help stabilize the light’s frequency.
“Using this shape [of an Archimedean spiral] 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,” Hansuek Lee, a senior researcher in Vahala’s lab and lead author on the paper.
In addition to being used as a frequency reference for lasers, researchers believe the device could be used to help efforts to shrink optical oscillators, which are considered better than electronic oscillators at delivering stable microwave and radio frequencies.
“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 said.
“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,” 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, said. “It opens up many new and unexplored options for building systems that could have greater impact to ‘real-world’ applications.”
