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A Portable Rubidium Fountain

Paul D. Kunz, Thomas P. Heavner, Steven R. Jefferts

Published Nov 1, 2010• 0 citations
OpenAlex

Abstract

Abstract : We are developing a transportable laser-cooled rubidium (Rb) atomic fountain frequency standard. Over the last year, we have built the Ramsey cavity and rubidium source oven and are preparing to assemble the physics package. We have also made numerous refinements to the laser package, including transitioning to a new style of laser diode, vastly improving the optical phase-locked loops (OPLL), and improving the optical spatial mode to get more power out of the optical fibers. These refinements have enabled the laser cooling to collect many more atoms, which will improve the fountain s signal-to-noise ratio.

Related papers

PROGRESS ON A PORTABLE RUBIDIUM FOUNTAIN FREQUENCY STANDARD

Paul D. Kunz, Thomas P. Heavner, Steven R. Jefferts

We are developing a transportable laser-cooled rubidium (Rb) atomic fountain frequency standard. We have a complete optical package, and have recently shown cooled, launched, and detected atoms. Additionally, a new physics package has been designed and is currently under construction. Here we describe the recent progress made on this project, including refinements to our optical package and its evaluation, and our design choices for the physics package.

•Aug 22, 2015•0 citations

A Simplified Laser and Optics System for Laser-Cooled RB Fountain Frequency Standards

Paul D. Kunz, Thomas P. Heavner, Steven R. Jefferts

We are developing a simple and robust laser and optics system suitable for a transportable laser-cooled rubidium (Rb) atomic fountain frequency standard. This system uses DFB (Distributed Feedback) diode lasers and a frequency offset-locking scheme to generate the optical frequencies needed for laser-cooling, launching, post-cooling, and detection of Rb atoms. Here, we describe the early results from this project and the anticipated performance of a compact, transportable Rb fountain frequency standard using this laser system. This system will also be useful for nontransportable laser-cooled atomic frequency standards.

•Nov 1, 2007•1 citation

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We present our recently experimental results on a DFB laser diode pumped Rubidium atomic frequency standard. Our experiment was based on a homemade lamp-pumped Rubidium frequency standard with the discharge lamp assembly removed. In the experiment, we first locked a DFB laser diode to the87Rb cycling transition (5S1/2, F=2→5P3/2, F=3) by means of saturation absorption locking technique. After that, we optimized the parameters carefully related to the clock performance, such as temperature of the physical package, amplitude of the modulation signal for the laser locking. The preliminary short-term stability of our clock is measured 5.25×10−12τ−1/2(1s<τ<100s).

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We use one DFB laser diode(780 nm) as the pumping source,which is based on a homemade traditional rubidium frequency standard with the discharge lamp assembly removed.The laser frequency is locked to the 87Rb cycling transition(52S1/2,F=2→52P3/2,F=3) by means of traditional saturation absorption locking technique and the microwave rubidium frequency standard locking loop is accomplished.The initial short-term stability of the rubidium clock is measured to be 3.7×10-12 τ-1/2(1~100 s).

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Frequency stability of a Rubidium Frequency Standard (RFS) is directly related to the signal-to-noise ratio (S/N) of the microwave-induced (6834 MHz) optical signal which is proportional to the fractional atomic population difference between the two M/sub F/=0 ground state sublevels of /sup 87/Rb. In the present RFSs this fractional population difference is small (>

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Compact 780-nm Rb optical clock

Zhendong Chen, Tianyu Liu, Ruoao Yang +9 more

We demonstrated a compact 780 nm rubidium optical clock, which includes an optical frequency standard and an optical frequency comb, with an optical volume of 11.6 liters. Unlike the 778 nm rubidium atomic clocks based on two-photon transition, here, the laser frequency is stabilized to the Rb D2 transition, using modulation transfer spectroscopy. This approach effectively eliminates Doppler background and provides a high signal to noise ratio and high sensitivity. A nearly 300 MHz microwave signal, whose phase exactly tracks that of the optical frequency standard, is generated via the optical frequency comb, yielding a frequency instability of 1.91 E-13 @1 s and 5.29 E-14 @1000 s in the electronic domain. To the best of our knowledge, this is the most precise frequency stabilization result for the first-excited-state transition of alkali metal atoms to date and represents the first optical clock based on this transition. These results offer a promising approach for the development of portable optical clocks.

arXiv:2501.01826•Physical Review Applied•Nov 24, 2025•4 citations
Abstract : We are developing a transportable laser-cooled rubidium (Rb) atomic fountain frequency standard. Over the last year, we have built the Ramsey cavity and rubidium source oven and are preparing to assemble the physics package. We have also made numerous refinements to the laser package, including transitioning to a new style of laser diode, vastly improving the optical phase-locked loops (OPLL), and improving the optical spatial mode to get more power out of the optical fibers. These refinements have enabled the laser cooling to collect many more atoms, which will improve the fountain s signal-to-noise ratio.
We are developing a simple and robust laser and optics system suitable for a transportable laser-cooled rubidium (Rb) atomic fountain frequency standard. This system uses DFB (Distributed Feedback) diode lasers and a frequency offset-locking scheme to generate the optical frequencies needed for laser-cooling, launching, post-cooling, and detection of Rb atoms. Here, we describe the early results from this project and the anticipated performance of a compact, transportable Rb fountain frequency standard using this laser system. This system will also be useful for nontransportable laser-cooled atomic frequency standards.
We present our recently experimental results on a DFB laser diode pumped Rubidium atomic frequency standard. Our experiment was based on a homemade lamp-pumped Rubidium frequency standard with the discharge lamp assembly removed. In the experiment, we first locked a DFB laser diode to the87Rb cycling transition (5S1/2, F=2→5P3/2, F=3) by means of saturation absorption locking technique. After that, we optimized the parameters carefully related to the clock performance, such as temperature of the physical package, amplitude of the modulation signal for the laser locking. The preliminary short-term stability of our clock is measured 5.25×10−12τ−1/2(1s<τ<100s).
We demonstrated a compact 780 nm rubidium optical clock, which includes an optical frequency standard and an optical frequency comb, with an optical volume of 11.6 liters. Unlike the 778 nm rubidium atomic clocks based on two-photon transition, here, the laser frequency is stabilized to the Rb D2 transition, using modulation transfer spectroscopy. This approach effectively eliminates Doppler background and provides a high signal to noise ratio and high sensitivity. A nearly 300 MHz microwave signal, whose phase exactly tracks that of the optical frequency standard, is generated via the optical frequency comb, yielding a frequency instability of 1.91 E-13 @1 s and 5.29 E-14 @1000 s in the electronic domain. To the best of our knowledge, this is the most precise frequency stabilization result for the first-excited-state transition of alkali metal atoms to date and represents the first optical clock based on this transition. These results offer a promising approach for the development of portable optical clocks.