Noise Investigation of a Dual-Frequency VECSEL for Application to Cesium Clocks

Liu, Hui; Gredat, Grégory; Baili, Ghaya; Gutty, François; Goldfarb, Fabienne; Sagnes, I.; Bretenaker, Fabien

doi:10.1109/jlt.2018.2852061

Cited by 20 publications

(37 citation statements)

References 25 publications

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“…This confirms the expectation that the full in-phase pumping combined with a very low non-linear coupling constant C are favorable conditions for the in-phase noise to dominate. Indeed, such a domination of the in-phase mechanism was predicted in [6], which states that decreasing the coupling between the two modes favors in-phase noise with respect to anti-phase noise. The dramatic anti-phase noise reduction corroborates the fact that the gain competition between the two modes is well inhibited.…”

Section: Device Implementation For Fully-correlated Pumpingmentioning

confidence: 85%

“…The beat note spectra are plotted versus the frequency offset from the carrier. The wider spectrum (in blue) corresponds to the single pump spot scheme reported in [6] whereas the other one (in orange) corresponds to the two fully in-phase correlated pumps. Figure 6 plots the power spectral density of phase fluctuations of the VECSEL beat note.…”

Section: Phase Noise Reductionmentioning

confidence: 99%

“…This latter condition plays though a marginal role to reduce the phase noise as soon as η 1, which is the case here. Figure 5 reports the VECSEL output beat note detected with a spectrum analyser in two respective conditions : with a single pump spot as reported in [6] (in blue) and with the two in-phase correlated pumps (in orange). As a consequence of the novel pumping scheme and as predicted, the beat note noise pedestal experiences a tremendous decrease.…”

Section: Phase Noise Reductionmentioning

confidence: 99%

“…Section 4 is dedicated to the analysis of the phase noise of the beat note. We perform a comparison with the previous studies [6,7], which use a single pump spot on the gain medium. Experimental results are also compared to the model developed in [6].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Fully–correlated multi–mode pumping for low–noise dual–frequency VECSELs

Gredat¹,

Chatterjee²,

Baili³

et al. 2018

Opt. Express

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We report a fully-correlated multi-mode pumping architecture optimized for dramatic noise reduction of a class-A dual-frequency Vertical External Cavity Surface Emitting Laser (VECSEL). Thanks to amplitude division of a laser diode, the two orthogonally polarized modes emitted by the VECSEL oscillating at 852 nm are separately pumped by two beams exhibiting fully in-phase correlated intensity noises. This is shown to lead to very strong and in-phase correlations between the two lasing modes intensities. As a result, the phase noise power spectral density of the RF beat note generated by the two modes undergoes a drastic reduction of about 10 to 20 dB throughout the whole frequency range from 10 kHz to 20 MHz and falls below the detection floor above a few MHz. A good agreement is found with a model which uses the framework of rate equations coupled by cross-saturation. The remaining phase noise is attributed to thermal effects and additional technical noises and lies mainly within the bandwidth of a phase-locked-loop.

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Section: Device Implementation For Fully-correlated Pumpingmentioning

confidence: 85%

Section: Phase Noise Reductionmentioning

confidence: 99%

Section: Phase Noise Reductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Fully–correlated multi–mode pumping for low–noise dual–frequency VECSELs

Gredat¹,

Chatterjee²,

Baili³

et al. 2018

Opt. Express

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“…For example, DF-laser beat-note stabilization has already been implemented in DBR fiber lasers with optical feedback [9] or optical phase-locked loops (OPLL) [10]. However, noise investigations in free running DF-VECSELs operating at cesium clock wavelength have shown that the intensity noise and the beat-note phase noise of the free running lasers mainly originate from the intensity noise of the pump laser [11]. The way this pump noise is transferred to the intensity and beat-note phase noises of the DF-VECSEL depends mainly on i) the laser dynamical behavior through the nonlinear coupling constant between the two laser modes and ii) the correlations between the noises of the pump power seen by the two modes.…”

Section: Introductionmentioning

confidence: 99%

Optimization of laser dynamics for active stabilization of DF-VECSELs dedicated to cesium CPT clocks

et al. 2020

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We report the implementation and performance of a double servo-loop for intensity and phasedifference active stabilization of a dual-frequency vertical external-cavity surface-emitting laser (DF-VECSEL) for coherent population trapping (CPT) of cesium atoms in the framework of compact atomic clocks. In-phase fully correlated pumping of the two laser modes is identified as the best scheme for intensity noise reduction, and an analytical model allows the optimization of the active stabilization strategy. Optical phase-locking the beat-note to a local oscillator leads to a phase noise level below-103 dBc/Hz at 100 Hz from the carrier. The laser contribution to the short-term frequency stability of the clock is predicted to be compatible with a targeted Allan deviation below σy = 5 × 10 −13 over one second.

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Thermal phase fluctuations in optically pumped dual-frequency vertical external-cavity surface-emitting lasers for cesium clocks based on coherent population trapping

Gredat

Liu

Bretenaker

2019

Journal of Applied Physics

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A fully analytical model is established for the thermal fluctuations of the beatnote phase of an optically pumped dual-frequency vertical-external-cavity surface-emitting laser (VECSEL). This model starts with the resolution of the heat equation inside the semiconductor chip structure and follows with the evaluation of the induced thermo-optic phase shift. Both the fluctuations of the heat induced by the optical pumping and the thermodynamic fluctuations at room temperature are considered. On the one hand, the thermal response of the structure is investigated and a significant thermal lens effect caused by the pump is deduced. On the other hand, the power spectral density of the frequency noise is calculated in the presence of diffusion spatial anisotropy. The present model is in very good agreement with the phase noise measured for a dual-frequency VECSEL at 852 nm for application to metrology and the validity of the usual low-pass filter model is discussed.

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Noise Investigation of a Dual-Frequency VECSEL for Application to Cesium Clocks

Cited by 20 publications

References 25 publications

Fully–correlated multi–mode pumping for low–noise dual–frequency VECSELs

Fully–correlated multi–mode pumping for low–noise dual–frequency VECSELs

Optimization of laser dynamics for active stabilization of DF-VECSELs dedicated to cesium CPT clocks

Thermal phase fluctuations in optically pumped dual-frequency vertical external-cavity surface-emitting lasers for cesium clocks based on coherent population trapping

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