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

Abstract

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.

Progress on a Highly Compact Cesium CPT Clock Based on a Dual-Frequency VECSEL

“…4) to inject the clock bench provides two linearly polarized orthogonal modes at 852 nm with adjustable frequency difference around 9.2 GHz. An optimized architecture of the pumping scheme has been developed to obtain in-phase correlated intensity noises between the two modes as well as low noise transfer from the pump laser to the VECSEL eigenstates [3]. First measurements show in-phase correlations between the two frequencies with a degree of correlation above 0.6 (Fig.…”

An innovative laser bench for a high performance compact cesium CPT clock

“…We propose to implement a highly compact set-up for a CPT clock based on a miniature electro-optical bench and a disruptive dual-frequency dual-polarization Vertical External Cavity Surface Emitting Laser (DF-VECSEL) that generates directly two eigenmodes at 852 nm separated by 9.192 GHz 2 with perpendicular polarizations needed for Lin per Lin interrogation 3 . The targeted relative frequency stability at 1 s of integration time is below 5×10 -13 , averaging down below 10 -14 at 1 h. Extensive studies of the power stabilization function of the bench has been done for both short and long time scales and interactions with a dual-frequency laser beam were described 4,5 . Here we present and discuss preliminary characterizations of simultaneous optical power stabilization and optical frequency locking of the laser within the complete miniature electro-optical bench.…”

Laser Intensity and Frequency Stabilization Implemented on a Miniature CPT Clock Breadboard

“…We propose to implement a highly compact set-up for a CPT clock based on a miniature electro-optical bench and a disruptive dual-frequency dual-polarization Vertical External Cavity Surface Emitting Laser (DF-VECSEL) that generates directly two eigenmodes at 852 nm separated by 9.192 GHz [2] with perpendicular polarizations needed for Lin per Lin interrogation [3]. The targeted relative frequency stability at 1 s of integration time is below 5×10 -13 .…”