Influence of laser sources with different spectral properties on the performance of vapor cell atomic clocks based on lin‖lin CPT

Abstract

We evaluate the influence of 2 types of laser sources with different spectral profiles on the performance of vapor cell atomic clocks based on lin||lin coherent population trapping (CPT) resonances. We show that a short-term stability of 1-2 x 10(-11) tau(-1/2) may be reached in a compact system using a modulated vertical cavity surface-emitting laser. Here the stability is limited by the detection noise level and can be improved up to a factor of 4 by increasing the lock-in detection frequency to several tens of kilohertz, which is not possible in standard double resonance atomic clocks. We compare these results with CPT prepared under the same experimental conditions, using 2 phase-locked extended cavity diode lasers, with which we predict a challenging short-term stability of 1-3 x 10(-13) tau(-1/2), comparable to the state-of-the-art laser-pumped Rb-clocks.

Light effects in the atomic-motion-induced Ramsey narrowing of dark resonances in wall-coated cells

“…9. These values are comparable with the performance predicted in a buffer gas cell with a laser source of higher spectral quality (two phase-locked extended cavity diode lasers [44]). From Fig.…”

Coherent-population-trapping resonances with linearly polarized light for all-optical miniature atomic clocks

“…This value implies a shot-noise-limited frequency stability of σ (τ ) ∼ 2 × 10 −14 τ 1/2 . In practice, however, the frequency stability will also be limited by residual intensity noise that depends strongly on the linewidth of the laser [22,23]. Recently, a table-top prototype atomic clock based on lin||lin CPT resonances with a short-term fractional frequency stability 2 × 10 −11 τ −1/2 was demonstrated [24].…”

All-optical compass based on the effect of electromagnetically induced transparency

“…Therefore, a high contrast of the resonances, where most of the atoms (50%-70%) are accumulated in the dark state [23][24][25], makes them a perspective competitor for existing all-optical magnetometers [21]. As an example, we estimate the achievable sensitivity using recently published data on the lin||lin resonances [26] (authors of [26] characterized the lin||lin resonances as an atomic clock reference). With a resonance width FWHM = 900 Hz and S/N = 3300 Hz 1/2 , the sensitivity for the measurable magnetic field is δB < 10 −11 T/Hz 1/2 , which can be obtained without special efforts and for very moderate density 10 10 cm −3 of rubidium atoms (50…”

“…• C and 1.2 Torr N 2 pressure in [26]). To significantly improve the sensitivity one should increase the number of atoms.…”