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

Applied Physics Letters

Oscillator-free atomic clock using a multimode laser

Sin Hyuk Yim, D. Cho

Published May 24, 2010• 7 citations
Publisher

Abstract

We developed an atomic clock using two modes from a single extended-cavity diode laser in multimode operation. The two modes are phase locked with reference to a dispersion signal from a coherent population trapping (CPT) resonance of R85b at 3.036 GHz. The design is in principle free from an oscillator and a modulator and it is a significant simplification over a conventional CPT-based atomic clock. Allan deviation of the beat frequency is 1×10−10 at 200 s integration time.

DOI
10.1063/1.3435474

Related papers

Production of a coherent pair of light beams with a microwave frequency difference from a single extended-cavity diode laser

Sin Hyuk Yim, D. Cho

We produced a pair of coherent laser beams with a 3-GHz frequency difference by optically phase locking two modes from a single, multimode extended-cavity diode laser. This method is complementary to either a direct modulation or an optical phase locking of two independent lasers. A large differential frequency shift between the two modes of the laser allows efficient phase locking. We developed a simple theory to account for the large differential frequency shift. Allan deviation of the beat frequency when the two modes are phase-locked drops as an inverse of the measurement time and it reaches 10(-14) when the time is 1 h. Coherent population trapping spectroscopy of Rb atoms using the phase-locked beams resulted in a spectrum as narrow as that of the case using direct modulation by a stable frequency synthesizer.

Review of Scientific Instruments•Feb 1, 2010•6 citations

CPT chip-scale atomic clock with direct-modulation chip-external cavity diode laser

Jiqing Lian, Jie Miao, Tian Zhao +7 more

Chip-scale atomic clocks are critical for applications requiring compact, energy-efficient, and highly stable timing, such as GPS receivers and communication systems. Coherent population trapping (CPT)-based atomic clocks, which commonly use vertical-cavity surface-emitting lasers (VCSELs), have enabled significant miniaturization. However, their precision is limited by the broad linewidth of VCSELs. Alternative laser technologies, such as distributed Bragg reflector lasers, distributed feedback lasers, and external cavity diode lasers (ECDLs), offer potential improvements but face challenges in achieving compact size and adequate modulation bandwidth. This study presents a 795 nm chip-ECDL with a direct modulation bandwidth up to 4 GHz, specifically designed for CPT chip-scale atomic clocks. Based on the chip-ECDL, a CPT atomic clock with a compact volume of 19.4 ml and power consumption of 1.5 W has been developed. Under identical operating conditions, the CPT signal produced by the chip-ECDL exhibits a 34% reduction in linewidth and a 1.14-fold increase in contrast compared to a VCSEL-based clock. Demonstrating short-term stability better than 5×10−11τ−1/2(1 s<τ<2000 s) and reaching a best stability of 6.6×10−13 at 2000 s, this work represents the application of an ECDL in a CPT chip-scale clock, advancing the development of next-generation, high-performance chip-scale atomic clocks.

Applied Physics Letters•Jun 2, 2025•9 citations

Stabilization method for atomic clocks to detect the maximum coherent-population-trapping resonance signal

Yusuke Odagiri, Satoshi Hatano, Yuichiro Yano +3 more

Abstract Chip-scale atomic clocks based on coherent population trapping (CPT) face challenges due to miniaturized gas cells, which reduces the CPT resonance signal and the absorption signals of alkali atoms. To overcome this, we propose a method that simultaneously stabilizes the laser wavelength and microwave modulation frequency without relying on absorption line detection. Our approach enables stabilization at the point where the amplitude of the CPT resonance signal is maximized, making it suitable for compact atomic clocks. The system uses three lock-in amplifiers: one is used to stabilize the RF modulation frequency, and the other two are used for detecting the amplitude of the CPT resonance and stabilizing the laser wavelength. The Allan deviation measurements demonstrate a 1.4-fold improvement in short-term stability compared to conventional methods, suggesting that the proposed technique is a promising solution for enhancing the performance of small gas-cell atomic clocks.

Japanese Journal of Applied Physics•Jun 1, 2025•2 citations

Optoelectronic oscillator stabilized to an intra-loop atomic filter with a coherent population trapping resonance

Sin Hyuk Yim, D. Cho

We report the construction and characterization of an optoelectronic oscillator stabilized to an intra-loop 85Rb cell with a 3.036-GHz coherent population trapping (CPT) resonance. We use an extended-cavity diode laser (ECDL) as a light source and directly modulate its injection current by using the beating signal filtered by the CPT resonance. Use of the ECDL guarantees stability of the carrier frequency and eliminates a bulky and power-consuming external modulator. We also adjust the cavity length and operate the ECDL in multimode in order to achieve a high modulation efficiency. To further improve the oscillator’s frequency stability, we incorporate a negative feedback system based on a CPT dispersion. The Allan deviation of the oscillator frequency is 3 × 10 −10 at a 100-s integration time.

Journal of the Korean Physical Society•Jul 1, 2012•3 citations

Atomic clock based on a coherent population trapping resonance in87Rb with improved high-frequency modulation parameters

Sergey Khripunov, Daba A. Radnatarov, Sergey M Kobtsev

This work reports for the first time development and experimental study of a laboratory prototype of an atomic clock with stability of 2×10–11τ –1/2 (Allan deviation) over time 1 s < τ < 1000 s (7×10–13 over 1000 s) on the basis of a coherent population trapping (CPT) resonance in 87Rb in a compact spherical cell having 1.3-cm diameter and without any buffer gas. Demonstrated are dependencies of the width of the studied CPT resonance upon the amplitude and modulation frequency of optical frequency difference (3.417 GHz) of a bichromatic circularly polarised pump field. For the first time, a considerable non-linearity was discovered in the dependence upon the reference difference frequency of the spectral position of the CPT resonance when the modulation frequency of the optical frequency difference is varied within a broad range.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Mar 10, 2015•19 citations

An atomic clock based on coherent population beating

Dawei Li, Daiting Shi, Ermeng Hu +4 more

We demonstrated an atomic clock based on coherent population beating (CPB). CPB occurs in typical Λ system, which enables us to obtain the beat frequency of the radio frequency for laser modulation and the hyperfine splitting. The beat frequency and its fluctuation is detected and accurately measured through digitized processing for compensating the shift of the radio frequency. It enables us to achieve a standard frequency which directly reference to the hyperfine transition. In our preliminary experiment an Allan Deviation of 3e-12 at 1000s is observed. CPB atomic clock eliminates the phase locking loop, and can be easily digitized and integrated.

Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)•May 1, 2014•0 citations
We developed an atomic clock using two modes from a single extended-cavity diode laser in multimode operation. The two modes are phase locked with reference to a dispersion signal from a coherent population trapping (CPT) resonance of R85b at 3.036 GHz. The design is in principle free from an oscillator and a modulator and it is a significant simplification over a conventional CPT-based atomic clock. Allan deviation of the beat frequency is 1×10−10 at 200 s integration time.
We produced a pair of coherent laser beams with a 3-GHz frequency difference by optically phase locking two modes from a single, multimode extended-cavity diode laser. This method is complementary to either a direct modulation or an optical phase locking of two independent lasers. A large differential frequency shift between the two modes of the laser allows efficient phase locking. We developed a simple theory to account for the large differential frequency shift. Allan deviation of the beat frequency when the two modes are phase-locked drops as an inverse of the measurement time and it reaches 10(-14) when the time is 1 h. Coherent population trapping spectroscopy of Rb atoms using the phase-locked beams resulted in a spectrum as narrow as that of the case using direct modulation by a stable frequency synthesizer.
Chip-scale atomic clocks are critical for applications requiring compact, energy-efficient, and highly stable timing, such as GPS receivers and communication systems. Coherent population trapping (CPT)-based atomic clocks, which commonly use vertical-cavity surface-emitting lasers (VCSELs), have enabled significant miniaturization. However, their precision is limited by the broad linewidth of VCSELs. Alternative laser technologies, such as distributed Bragg reflector lasers, distributed feedback lasers, and external cavity diode lasers (ECDLs), offer potential improvements but face challenges in achieving compact size and adequate modulation bandwidth. This study presents a 795 nm chip-ECDL with a direct modulation bandwidth up to 4 GHz, specifically designed for CPT chip-scale atomic clocks. Based on the chip-ECDL, a CPT atomic clock with a compact volume of 19.4 ml and power consumption of 1.5 W has been developed. Under identical operating conditions, the CPT signal produced by the chip-ECDL exhibits a 34% reduction in linewidth and a 1.14-fold increase in contrast compared to a VCSEL-based clock. Demonstrating short-term stability better than 5×10−11τ−1/2(1 s<τ<2000 s) and reaching a best stability of 6.6×10−13 at 2000 s, this work represents the application of an ECDL in a CPT chip-scale clock, advancing the development of next-generation, high-performance chip-scale atomic clocks.
Abstract Chip-scale atomic clocks based on coherent population trapping (CPT) face challenges due to miniaturized gas cells, which reduces the CPT resonance signal and the absorption signals of alkali atoms. To overcome this, we propose a method that simultaneously stabilizes the laser wavelength and microwave modulation frequency without relying on absorption line detection. Our approach enables stabilization at the point where the amplitude of the CPT resonance signal is maximized, making it suitable for compact atomic clocks. The system uses three lock-in amplifiers: one is used to stabilize the RF modulation frequency, and the other two are used for detecting the amplitude of the CPT resonance and stabilizing the laser wavelength. The Allan deviation measurements demonstrate a 1.4-fold improvement in short-term stability compared to conventional methods, suggesting that the proposed technique is a promising solution for enhancing the performance of small gas-cell atomic clocks.
We report the construction and characterization of an optoelectronic oscillator stabilized to an intra-loop 85Rb cell with a 3.036-GHz coherent population trapping (CPT) resonance. We use an extended-cavity diode laser (ECDL) as a light source and directly modulate its injection current by using the beating signal filtered by the CPT resonance. Use of the ECDL guarantees stability of the carrier frequency and eliminates a bulky and power-consuming external modulator. We also adjust the cavity length and operate the ECDL in multimode in order to achieve a high modulation efficiency. To further improve the oscillator’s frequency stability, we incorporate a negative feedback system based on a CPT dispersion. The Allan deviation of the oscillator frequency is 3 × 10 −10 at a 100-s integration time.
This work reports for the first time development and experimental study of a laboratory prototype of an atomic clock with stability of 2×10–11τ –1/2 (Allan deviation) over time 1 s < τ < 1000 s (7×10–13 over 1000 s) on the basis of a coherent population trapping (CPT) resonance in 87Rb in a compact spherical cell having 1.3-cm diameter and without any buffer gas. Demonstrated are dependencies of the width of the studied CPT resonance upon the amplitude and modulation frequency of optical frequency difference (3.417 GHz) of a bichromatic circularly polarised pump field. For the first time, a considerable non-linearity was discovered in the dependence upon the reference difference frequency of the spectral position of the CPT resonance when the modulation frequency of the optical frequency difference is varied within a broad range.
We demonstrated an atomic clock based on coherent population beating (CPB). CPB occurs in typical Λ system, which enables us to obtain the beat frequency of the radio frequency for laser modulation and the hyperfine splitting. The beat frequency and its fluctuation is detected and accurately measured through digitized processing for compensating the shift of the radio frequency. It enables us to achieve a standard frequency which directly reference to the hyperfine transition. In our preliminary experiment an Allan Deviation of 3e-12 at 1000s is observed. CPB atomic clock eliminates the phase locking loop, and can be easily digitized and integrated.