Future 'comb on a chip': NIST's compact frequency comb could go places
Laser frequency combs -- extraordinarily precise tools for measuring frequencies (or colors) of light -- have helped propel advances in timekeeping, trace gas detection and related physics research to new heights in the past decade. While typical lasers operate at only a single or handful of frequencies, laser frequency combs operate simultaneously at many frequencies, approaching a million for some combs. These combs have very fine, evenly spaced "teeth," each a specific frequency, which can be used like hash marks on a ruler to measure the light emitted by lasers, atoms, stars or other objects. But frequency combs are usually bulky, delicate lab instruments -- about the size of a typical suitcase -- and challenging to operate, which limits their use.