Laser Pump Noise Effects on the Stability of Optical Clockworks

University Of California-Davis, Davis CA

Investigators

Abstract

Laser Pump Noise Effects on the Stability of Optical Clockworks 0622235 Dr. Brian Kolner, UC Davis Intellectual Merit: The recent invention of f-2f self-referencing modelocked laser clockworks has heralded a new era in precision time and frequency metrology. In spite of phenomenal advances, there are still unanswered questions about the fundamental performance limits which might be expected from these clocks. This project will investigate an important component of laser clock performance; that of laser amplitude and phase fluctuations induced by noise in the pump source. The coupling mechanisms to be studied include perturbations to the: 1) complex susceptibility through the energy level populations, 2) length of the gain medium (thermal), 3) index of refraction (direct thermal), 4) index due to thermally-induced stress, 5) photon number, and 6) nonlinear index (Kerr-effect). These mechanisms combine to degrade the performance of the laser when the pump contains random noise. By inducing small-signal modulations on the pump beam, the magnitude of these effects will be measured and compared with theory. They will then be used to predict the ultimate performance of modelocked laser clocks and provide guidance toward better clock designs. Finally, f-2f interferometer control loops will be installed on two separate lasers to compare the closed-loop performance against predictions from theory. Broader Impacts: Precision time and frequency standards form the very foundation of navigation, commerce, telecommunications and many branches of science and technology. Improved clock precision will affect all aspects of human life. It will be especially significant in pushing the frontiers of fundamental science as we explore atoms and molecules with ever-higher precision, test whether or not the ``constants of nature'' are truly constant and improve our theories of cosmology. The results of this work will be incorporated into classroom lectures in the Optical Science and Engineering program at UC Davis and will also attract the attention of students outside of the program who are naturally fascinated by the fundamental limits of technology and how they advance basic science.