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Performance of a Microwave Clock Based on a Laser-Induced Stimulated Raman Interactions

Philip Hemmer, Shaoul Ezekiel, C. C. Leiby

Published Jun 18, 1984• 2 citations
OpenAlex

Abstract

Recent experimental work1 has demonstrated that a microwave oscillator can be stabilized using a stimulated-resonance Raman transition in a sodium atomic beam. This Raman technique is of interest because optical lasers rather than microwaves are used in the interaction, and, aside from fundamental interest, the greater flexibility of optical systems may make it possible eventually to develop more-stable and moreportable atomic clocks.

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Precision studies of stimulated-resonance Raman interactions in a sodium atomic beam were performed with emphasis on Ramsey’s separated-field excitation. Ramsey fringes were obtained for a field separation of up to 30 cm, and the data were consistent with theoretical predictions. Possible applications of this Raman interaction to clock development also were studied by stabilizing a microwave oscillator to a Raman–Ramsey fringe. The resulting oscillator stability of 1.5 × 10−11 for a 1000-sec averaging time compares favorably with commercial cesium clocks when differences in atom transit time and transition frequency are taken into consideration. Finally, potential sources of long-term frequency error, which are important for clock applications, were also partially investigated.

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Performance of a microwave clock based on a laser-induced stimulated Raman interaction (A)

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Abstract The atomic clocks, whether operating at optical or microwave region, can be divided into two categories according to their working mode, namely the passive clocks and active clocks. The passive clocks, whose standard frequency is locked to an ultra-narrow atomic spectral line, such as laser cooled Cs beam or lattice trapped Sr atoms, depend on the spontaneous emission line. On the contrary, the active clocks, in which the atoms are used as the gain medium, are based on the stimulated emission radiation, their spectrum can be directly used as the frequency standard. Up to now, the active hydrogen maser has been the most stable microwave atomic clocks. Also, the Sr superradiant active atomic clock is prospects for a millihertz-linewidth laser. Moreover, the optical clocks are expected to surpass the performance of microwave clocks both in stability and uncertainty, since their higher working frequency. The active optical clock has the potential to improve the stability of the best clocks by 2 orders of magnitude. In this work, we introduce the development of active optical clocks, and their types is classified according to the energy-level structure of atoms for stimulated radiation.

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Physics of Atomic Frequency Standards Based on Stimulated Resonance Raman Scattering

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Abstract : This report analyzes a novel technique developed at RADC for high-precision frequency standards operating in the microwave to far infrared regions of the spectrum. The technique is based on stimulated resonance Raman scattering of visible laser light in atomic or molecular beams; it does not require low frequency (microwave to far infrared) radiation to interact with the resonant species, and it is potentially capable of stabilities characteristic of low-frequency atomic standards.

Unknown eBooks•Oct 1, 1981•0 citations
Recent experimental work1 has demonstrated that a microwave oscillator can be stabilized using a stimulated-resonance Raman transition in a sodium atomic beam. This Raman technique is of interest because optical lasers rather than microwaves are used in the interaction, and, aside from fundamental interest, the greater flexibility of optical systems may make it possible eventually to develop more-stable and moreportable atomic clocks.
Precision studies of stimulated-resonance Raman interactions in a sodium atomic beam were performed with emphasis on Ramsey’s separated-field excitation. Ramsey fringes were obtained for a field separation of up to 30 cm, and the data were consistent with theoretical predictions. Possible applications of this Raman interaction to clock development also were studied by stabilizing a microwave oscillator to a Raman–Ramsey fringe. The resulting oscillator stability of 1.5 × 10−11 for a 1000-sec averaging time compares favorably with commercial cesium clocks when differences in atom transit time and transition frequency are taken into consideration. Finally, potential sources of long-term frequency error, which are important for clock applications, were also partially investigated.
The usefulness of stimulated Raman transitions has been demonstrated in a variety of different applications. These two-photon transitions have the capability of very high resolution because the transition linewidths depend on the relative jitter between two frequencies, rather than absolute jitter on either one. Recent demonstrations include laser cooling and atomic interferometry [1]. They may also be needed for improved atomic clocks [2]. Due to this high resolution, stimulated Raman transitions can be a direct replacement for a microwave cavity and are often more compatible with optical experiments because a laser beam requires less space.
Abstract The atomic clocks, whether operating at optical or microwave region, can be divided into two categories according to their working mode, namely the passive clocks and active clocks. The passive clocks, whose standard frequency is locked to an ultra-narrow atomic spectral line, such as laser cooled Cs beam or lattice trapped Sr atoms, depend on the spontaneous emission line. On the contrary, the active clocks, in which the atoms are used as the gain medium, are based on the stimulated emission radiation, their spectrum can be directly used as the frequency standard. Up to now, the active hydrogen maser has been the most stable microwave atomic clocks. Also, the Sr superradiant active atomic clock is prospects for a millihertz-linewidth laser. Moreover, the optical clocks are expected to surpass the performance of microwave clocks both in stability and uncertainty, since their higher working frequency. The active optical clock has the potential to improve the stability of the best clocks by 2 orders of magnitude. In this work, we introduce the development of active optical clocks, and their types is classified according to the energy-level structure of atoms for stimulated radiation.