NIST researchers have successfully transferred ultraprecise time signals over a wireless optical channel between two locations approximately two kilometers apart. The two-way technique overcomes timing distortions caused by atmospheric turbulence and demonstrates how next-generation atomic clocks at different locations could be linked wirelessly.
The demonstration shows potential for improved distribution of time and frequency information, geodesy (altitude mapping), satellite navigation, radar arrays, and other applications. The stability of the transferred infrared signal matched that of NIST’s best experimental atomic clock, operating at optical frequencies.
The signal transfer was performed using two laser frequency combs, which generate a steady stream of ultrashort optical pulses synchronized with the “ticks” of an optical atomic clock. The technique can operate at much longer distances and potentially over future ground-to-satellite optical communication links as an added timing channel.
Keywords: Atomic Clocks, Infrared Signal, Frequency Instabilities, Laser Frequency Combs, Optical Clock Signals
