Ultrahigh coherent semiconductor lasers and their applications to Rb atomic clock

Lute Maleki, Anatoliy A. Savchenkov, Wei Ge Liang +4 more

This paper presents a novel architecture for a high performance atomic clock based on the use of miniature optical whispering gallery mode (WGM) resonators. Following the approach of stabilizing a laser local oscillator to an optical transition in an atom or ion, as used in advanced atomic clock, a semiconductor laser is used for stabilization to the D1 line of Rb atoms, held in a small vapor cell. The laser is self-injection locked to a WGM resonator to reduce its linewidth. To produce the RF output of the clock, a second WGM resonator excited with a second cw semiconductor laser produces an optical frequency comb that is demodulated on a fast photodiode. Locking the resonator that generates the frequency comb to the laser stabilized to the Rb transition transfers the stability of the atomic transition to the RF output of the clock. In this way, a miniature all-optical atomic clock is realized. Details of the operation of the clock and application of the architecture to other atomic systems, such as a ytterbium ion, will be described.

Florian Emaury, Oğuzhan Kara, Jonas Heidrich +1 more

Xi Zeng

Atomic clocks are a vital technology in the day to day operation of modern society. While passive Rb and Cs microwave atomic clocks find widespread practical applications today, active atomic clocks have the potential to surpass them in frequency stability, compactness, and simplicity. This dissertation is a comprehensive study of the physics of an active atomic clock based on modelocked external cavity semiconductor laser with 85Rb vapor cell saturable absorber. As the starting point for establishing our concept, this study encompasses optical interrogation in the traditional D1 (5S1/2-5P1/2, 795 nm wavelength) line in 85Rb atoms, as well as in the less used and less studied 5S1/2-6P3/2 (420 nm) line, which has very different absorption characteristics. The theoretical and experimental work in this dissertation establish a foundational background for the active atomic clock laser, yielding novel results in the field of semiconductor lasers and atomic physics.

Zhuang, Chen

Daba A. Radnatarov, Sergey M Kobtsev, Valeriy Andryushkov +1 more

Presented for the first time is our research into reduction of energy consumption of miniaturised Rb atomic clocks based on coherent population trapping (CPT) effect at lowered microwave modulation frequency. We studied properties of a CPT-based atomic frequency standard pumped with multi-frequency radiation from sidebands of a single-frequency semiconductor laser whose injection current was modulated at subharmonics (1/2–1/6) of the frequency of Rb hyperfine ground state splitting. Pumping by third-order sidebands is the optimum when the atomic clock stability drops only slightly (by 11%), whereas energy consumption of the microwave components is reduced by a factor of 1.5.

Howard M. Wiseman, John A. Vaccaro