Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Europhysics Letters (EPL)

Multipulse Ramsey-CPT interference fringes for the 87 Rb clock transition

Peter Yun, Yi Zhang, Guobin Liu, Wei Deng, Li You, Sihong Gu

Published Mar 1, 2012• 22 citations
Publisher

Abstract

Multipulse Ramsey-coherent population trapping (CPT) interference is implemented in a compact 87Rb atomic vapor cell. With the addition of an acousto-optic modulator (AOM), a fully integrated vertical-cavity surface-emitting laser (VCSEL) is slaved to operate in pulsed mode with precise temporal control. Our study reveals interesting characteristics and provides valuable insights into the application of Ramsey-CPT interference fringes for low-cost atomic clocks.

DOI
10.1209/0295-5075/97/63004

Related papers

Exploring Ramsey-coherent population trapping atomic clock realized with pulsed microwave modulated laser

Jing Yang, Yuan Tian, Bozhong Tan +2 more

A scheme for a Ramsey-coherent population trapping (CPT) atomic clock that eliminates the acousto-optic modulator (AOM) is proposed and experimentally studied. Driven by a periodically microwave modulated current, the vertical-cavity surface-emitting laser emits a continuous beam that switches between monochromatic and multichromatic modes. Ramsey-CPT interference has been studied with this mode-switching beam. In eliminating the AOM, which is used to generate pulsed laser in conventional Ramsey-CPT atomic clock, the physics package of the proposed scheme is virtually the same as that of a conventional compact CPT atomic clock, although the resource budget for the electronics will slightly increase as a microwave switch should be added. By evaluating and comparing experimentally recorded signals from the two Ramsey-CPT schemes, the short-term frequency stability of the proposed scheme was found to be 46% better than the scheme with AOM. The experimental results suggest that the implementation of a compact Ramsey-CPT atomic clock promises better frequency stability.

Journal of Applied Physics•Mar 7, 2014•15 citations

Operation of a Ramsey-CPT microcell atomic clock with driving current-based power modulation of a VCSEL

C. M. Rivera-Aguilar, Martin Callejo, Andrei Mursa +6 more

We report on the operation of a coherent population trapping (CPT) microcell atomic clock using a pulsed Ramsey-like interrogation. The Ramsey-CPT sequence, defined by two-step optical pulses separated by a free-evolution dark time, is produced by switching on and off the output power of a low-power vertical-cavity surface-emitting laser, through direct modulation of its driving current. High-contrast and narrow Ramsey-CPT fringes are detected without the use of any external optical modulator stage. We demonstrate closed-loop operation of the clock based on high-speed digital signal processing implemented in a field programmable gate array board. The clock's short-term fractional frequency stability is 1.3 × 10−10τ−1/2 until 2000 s. A power light-shift coefficient of 8 × 10−11/μW, in relative value, is obtained for a dark time of 150 μs. This value is about ten times lower than in the continuous regime. These results show the feasibility of fully integrated atomic clocks based on Ramsey spectroscopy, which could provide enhanced long-term stability.

Applied Physics Letters•Mar 11, 2024•9 citations

CPT pulse excitation method based on VCSEL current modulation for miniature atomic clocks

Takumi Ide, Shigeyoshi Goka, Yuichiro Yano

We propose a coherent population trapping (CPT) pulsed-excitation method based on direct drive-current modulation of a vertical-cavity surface-emitting LASER for miniature atomic clocks (MACs). Because our method needs only a simple device configuration without optical external modulators, it is suitable for MACs, including chip-scale atomic-clocks. Reducing the size, cost, and power consumption is also possible. Additionally, we report on experimental results for Ramsey-CPT fringes excited using the proposed method.

Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)•Apr 1, 2015•10 citations

Prospect for development of a pulsed CPT Raman Ramsey clock using atomic vapor

G. S. Pati, Fredrik K. Fatemi, Mark Bashkansky +1 more

The phenomenon of all-optical Ramsey interference using pulsed coherent population trapping (CPT) beams provides a new avenue for developing frequency standards using atomic vapor. In this study, we show that frequency narrowed Ramsey fringes can be produced in rubidium vapor without the effect of power broadening. We observed fringes of width as narrow as 1 kHz using a buffer-gas filled rubidium cell. A compact injection-locked laser (ILL) system was used to generate CPT beams. Studies also show that ac Stark effect on Ramsey fringes can be reduced, and higher frequency stability can be achieved in a clock application. The results are encouraging to propose an architecture for development of a pulsed CPT Ramsey clock. In this paper, we also provide related discussions on clock frequency stability, and our plans for future experiments.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Feb 11, 2010•2 citations

Two-step pulse observation for Raman–Ramsey coherent population trapping atomic clocks

Yuichiro Yano, Shigeyoshi Goka, Masatoshi Kajita

We propose a two-step pulse observation method to enhance the frequency stability of coherent population trapping (CPT) atomic clocks. The proposed method is a Raman–Ramsey scheme with low light intensity at resonance observation and provides a Ramsey-CPT resonance with both reduced frequency sensitivity to the light intensity and a high signal-to-noise ratio by reducing the repumping into a steady dark state. The resonance characteristics were calculated using density matrix analysis of a Λ-type three-level system that was modeled on the 133 Cs D 1 line, and the characteristics were also measured using a vertical-cavity surface-emitting laser and a Cs vapor cell.

arXiv:1411.3779•Applied Physics Express•Dec 11, 2014•8 citations

Performance of a prototype atomic clock based on lin‖lin coherent population trapping resonances in Rb atomic vapor

Eugeniy E. Mikhailov, Travis Horrom, Nathan Belcher +1 more

We report on the performance of the first table-top prototype atomic clock based on coherent population trapping (CPT) resonances with parallel linearly polarized optical fields (lin‖lin configuration). Our apparatus uses a vertical-cavity surface-emitting laser (VCSEL) tuned to the D1 line of 87Rb with the current modulation at the 87Rb hyperfine frequency. We demonstrate cancellation of the first-order light shift by the proper choice of rf modulation power and further improve our prototype clock stability by optimizing the parameters of the microwave lock loop. Operating in these optimal conditions, we measured a short-term fractional frequency stability (Allan deviation) 2×10−11τ−1/2 for observation times 1 s ≤ τ ≤ 20 s. This value is limited by large VCSEL phase noise and environmental temperature fluctuation. Further improvements in frequency stability should be possible with an apparatus designed as a dedicated lin‖lin CPT resonance clock with environmental impacts minimized.

arXiv:0910.5881•Journal of the Optical Society of America B•Feb 3, 2010•53 citations
Multipulse Ramsey-coherent population trapping (CPT) interference is implemented in a compact 87Rb atomic vapor cell. With the addition of an acousto-optic modulator (AOM), a fully integrated vertical-cavity surface-emitting laser (VCSEL) is slaved to operate in pulsed mode with precise temporal control. Our study reveals interesting characteristics and provides valuable insights into the application of Ramsey-CPT interference fringes for low-cost atomic clocks.
A scheme for a Ramsey-coherent population trapping (CPT) atomic clock that eliminates the acousto-optic modulator (AOM) is proposed and experimentally studied. Driven by a periodically microwave modulated current, the vertical-cavity surface-emitting laser emits a continuous beam that switches between monochromatic and multichromatic modes. Ramsey-CPT interference has been studied with this mode-switching beam. In eliminating the AOM, which is used to generate pulsed laser in conventional Ramsey-CPT atomic clock, the physics package of the proposed scheme is virtually the same as that of a conventional compact CPT atomic clock, although the resource budget for the electronics will slightly increase as a microwave switch should be added. By evaluating and comparing experimentally recorded signals from the two Ramsey-CPT schemes, the short-term frequency stability of the proposed scheme was found to be 46% better than the scheme with AOM. The experimental results suggest that the implementation of a compact Ramsey-CPT atomic clock promises better frequency stability.
We report on the operation of a coherent population trapping (CPT) microcell atomic clock using a pulsed Ramsey-like interrogation. The Ramsey-CPT sequence, defined by two-step optical pulses separated by a free-evolution dark time, is produced by switching on and off the output power of a low-power vertical-cavity surface-emitting laser, through direct modulation of its driving current. High-contrast and narrow Ramsey-CPT fringes are detected without the use of any external optical modulator stage. We demonstrate closed-loop operation of the clock based on high-speed digital signal processing implemented in a field programmable gate array board. The clock's short-term fractional frequency stability is 1.3 × 10−10τ−1/2 until 2000 s. A power light-shift coefficient of 8 × 10−11/μW, in relative value, is obtained for a dark time of 150 μs. This value is about ten times lower than in the continuous regime. These results show the feasibility of fully integrated atomic clocks based on Ramsey spectroscopy, which could provide enhanced long-term stability.
We propose a coherent population trapping (CPT) pulsed-excitation method based on direct drive-current modulation of a vertical-cavity surface-emitting LASER for miniature atomic clocks (MACs). Because our method needs only a simple device configuration without optical external modulators, it is suitable for MACs, including chip-scale atomic-clocks. Reducing the size, cost, and power consumption is also possible. Additionally, we report on experimental results for Ramsey-CPT fringes excited using the proposed method.
The phenomenon of all-optical Ramsey interference using pulsed coherent population trapping (CPT) beams provides a new avenue for developing frequency standards using atomic vapor. In this study, we show that frequency narrowed Ramsey fringes can be produced in rubidium vapor without the effect of power broadening. We observed fringes of width as narrow as 1 kHz using a buffer-gas filled rubidium cell. A compact injection-locked laser (ILL) system was used to generate CPT beams. Studies also show that ac Stark effect on Ramsey fringes can be reduced, and higher frequency stability can be achieved in a clock application. The results are encouraging to propose an architecture for development of a pulsed CPT Ramsey clock. In this paper, we also provide related discussions on clock frequency stability, and our plans for future experiments.
We propose a two-step pulse observation method to enhance the frequency stability of coherent population trapping (CPT) atomic clocks. The proposed method is a Raman–Ramsey scheme with low light intensity at resonance observation and provides a Ramsey-CPT resonance with both reduced frequency sensitivity to the light intensity and a high signal-to-noise ratio by reducing the repumping into a steady dark state. The resonance characteristics were calculated using density matrix analysis of a Λ-type three-level system that was modeled on the 133 Cs D 1 line, and the characteristics were also measured using a vertical-cavity surface-emitting laser and a Cs vapor cell.
We report on the performance of the first table-top prototype atomic clock based on coherent population trapping (CPT) resonances with parallel linearly polarized optical fields (lin‖lin configuration). Our apparatus uses a vertical-cavity surface-emitting laser (VCSEL) tuned to the D1 line of 87Rb with the current modulation at the 87Rb hyperfine frequency. We demonstrate cancellation of the first-order light shift by the proper choice of rf modulation power and further improve our prototype clock stability by optimizing the parameters of the microwave lock loop. Operating in these optimal conditions, we measured a short-term fractional frequency stability (Allan deviation) 2×10−11τ−1/2 for observation times 1 s ≤ τ ≤ 20 s. This value is limited by large VCSEL phase noise and environmental temperature fluctuation. Further improvements in frequency stability should be possible with an apparatus designed as a dedicated lin‖lin CPT resonance clock with environmental impacts minimized.