Two lasers help shrink a light-measuring tool toward portable clocks

Researchers at NIST and the Joint Quantum Institute have demonstrated a new way to produce a miniature frequency comb, a tool that lets scientists compare light frequencies precisely. The advance could help reduce the equipment needed for optical atomic clocks, according to NIST’s October 16 report. It is a laboratory result, with portable applications still ahead. ^[1]

A frequency comb supplies regularly spaced reference frequencies, functioning like measurement marks for light. The team directed two lasers around a tiny ring on a chip. Their interactions produced a comb while addressing stability problems that can leave earlier designs dependent on additional equipment. That matters because shrinking the chip alone does not make an entire measurement system portable. ^[1]

The Joint Quantum Institute’s account describes how the new approach aligns overlapping frequency lines that had complicated an earlier two-laser demonstration. Researchers also tested one device in several measurement arrangements, including comparisons involving optical and microwave signals. Checks against a conventional tabletop comb helped establish that the miniature device could reproduce the relevant measurement performance under those experimental conditions. ^[2]

NIST identifies navigation when GPS is unavailable or disrupted as a possible use for future compact clocks. The immediate achievement is narrower: a component and a method that could support that work. The institute’s research account says further refinements are planned. Readers should therefore distinguish the demonstrated optical measurements from a finished clock or a navigation system proven in everyday service. ^[2]

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