NIST Demonstrates Portable Chip-Based Light Measurement Device

Researchers at the National Institute of Standards and Technology and their colleagues have demonstrated a new way to generate a miniature tape measure for light. Unlike previous designs, it can make high-quality optical measurements without needing to be tethered to bulky laboratory equipment.

The miniature instruments are known as microchip frequency combs. They generate a spectrum of precise, evenly spaced colors that act like tick marks on a ruler to measure the frequencies of light with extraordinary accuracy.

The devices are fabricated on wafers. Each wafer contains more than 400 chips. Each chip houses up to 300 tiny ring-shaped resonators that form the heart of the technology.

Scientists at NIST and JQI, a research partnership between NIST and the University of Maryland, send light from two lasers around a tiny ring known as a microresonator. The light interacts with itself to produce the evenly spaced tick marks of a comb.

The technique avoids a problem associated with previous single-laser methods, which required additional power-hungry equipment to produce stable high-quality tick marks.

Frequency combs are essential components of optical atomic clocks, which produce extremely precise timing signals. The new device could help revolutionize ultraprecise mobile timekeeping.

Mobile optical clocks could provide vital navigation signals for drones, cars, submarines and other vehicles when GPS is either unavailable or has been jammed. They could also be used for military navigation and oil, gas and mineral exploration.