A highly stable frequency-stabilized extended-cavity diode laser for space

Abstract

EADS SODERN is developing a compact highly stable near infrared laser dedicated to a space cold atom clock (PHARAO program supported by the CNES). The laser is based on an extended cavity diode laser (ECDL). We will present the design, preliminary performances and the environment behaviour of this ECDL. The ECDL is spectrally tuned with an intra-cavity Fabry-Perot filter. It emits 30mW laser power at a wavelength of 852nm with a line-width around 100kHz. The laser frequency is servo-locked on a saturated absorption line of a cesium vapour. It provides a relative frequency accuracy of 3x10^-9 and a frequency noise spectral density lower than 10⁴Hz²/Hz in the range 100Hz to 1kHz. An acousto-optic modulator enables a fast and accurate tuning of the laser frequency, over a 80MHz range, with a rising time of 200GHz/s. According to the results of the mock-up, the flight model under development is expected to be the most accurate and stable laser for space. Beyond the intended application of space-based cold atom clock, such a stabilized laser could also be a key element for future on-board instruments such as space interferometers or space LIDAR, for which a highly stable optical frequency standard is required.