Like a vocal coach who extends the octave range of an opera singer, researchers at the National Institute of Standards and Technology (NIST) have expanded by nearly two-thirds the frequency range over which a chip-scale device can generate and measure the oscillations of light waves with exquisite accuracy. The expanded range of the system, known as a microring resonator frequency comb, or microcomb, could lead to better sensors of greenhouse gases and may also improve global navigation systems.
Gregory Moille and his colleagues at NIST, including team leader Kartik Srinivasan, along with collaborators at the Joint Quantum Institute (a NIST-University of Maryland research partnership) and the University of Maryland, reported their findings in the December 14, 2021 issue of Nature Communications.
A frequency comb acts like the optical version of a ruler. Just as a ruler, divided into hundreds of tick marks spaced a known distance apart, measures an object of unknown length, a frequency comb features hundreds of different ultrasharp, uniformly spaced frequency spikes to precisely measure light of an unknown frequency (The tool is so named because the frequency spikes resemble the teeth of a comb.)
Microring resonator animation
By using two lasers instead of one, NIST researchers have developed a method for nearly doubling the range of the frequency comb generated by a microring resonator. Credit: S. Kelley/NIST
Over the past two decades, scientists at NIST and other research institutions have shown that microcombs can play an important role in building highly accurate o ..
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