High Stability Optical Oscillators -- Precise Timing from Optical to Microwaves
Seminar by
Dr. Leo Hollberg
NIST - Boulder

Abstract: Optical frequency references now provide unprecedented performance in frequency stability and timing precision. These optical references based on stable cw lasers combined with mode-locked optical frequency combs have several advantages over electronic systems, including very low loss, high Q’s, and ultra-short pulses (fs scale). Laboratory experiments demonstrate sub-femtosecond timing jitter, fractional frequency instabilities of < 10-15, and can provide microwave signals with ultra-low phase-noise. The technology is providing exceptional performance that enables rapid progress in precision spectroscopy, optical atomic clocks, tests of fundamental physics, and in some advanced timing applications. On short time scales, optical resonators provide the highest stability while for longer times atomic resonances have better performance. The optimal crossover time from physical resonators to atoms will depend on several factors, but might be in the range of 0.1 to 10 seconds. A review of the present state of the technology, capabilities and limitations, will be provide along with some speculation about prospects for the future.

 Bio: Leo Hollberg graduated from Stanford University in 1976 with a B.S. in physics. He went on to complete a PhD in physics at the University of Colorado for research in high-resolution laser spectroscopy done under the supervision of Jan Hall at JILA. Most of 1984 and 1985 were spent at AT&T Bell Laboratories as a postdoc working with the Steven Chu on laser cooling and trapping of atoms, and with Richart Slusher on squeezed states of light. Since then he has been at NIST doing research on high-resolution spectroscopy of laser-cooled and -trapped atoms, the development of semiconductor lasers for scientific and technical applications, optical coherence effects of driven multilevel atoms, chip-scale-atomic-clocks, optical frequency standards, optical frequency combs and optical atomic clocks. Areas of expertise include frequency stabilized lasers with ultra-narrow linewidths and high resolution optical spectroscopy and optical frequency standards. Much of this research is done in collaboration with his NIST colleagues and with scientists from around the world. Leo is currently the group leader of the Optical Frequency Measurements group in the Time and Frequency Division, NIST, Boulder.