A laser setup for rubidium cooling dedicated to space applications

Abstract

We present the complete characterization of a laser setup for rubidium cooling dedicated to space applications. The experimental setup is realized with commercial off-the-shelf fiber components suitable for space applications. By frequency doubling two fiber laser diodes at 1560 nm, we produce the two optical frequencies at 780 nm required for atomic cooling of ⁸⁷Rb. The first laser is locked on saturated absorption signal and long-term frequency drift has been canceled using a digital integrator. The optical frequency of the second laser is controlled relatively to the first one by a frequency comparison method. A full characterization of the setup, including frequency stability evaluation and frequency noise measurement, has been performed. The optical frequency doubling module has been submitted to environmental tests to verify its compatibility with space applications.

Environmental tests

In this part, we give the results of the life tests and environmental tests performed on the wavelength conversion module. The conversion efficiency η and the phase-matching temperature T _pm were measured for an input power of P _in = 20 mW before and after each test. These two parameters are determined with a respective relative uncertainty of 13 and 5% at 3σ. The life tests, reported in Table 1, were performed during 2000 h on three different devices (D1, D2 and D3). The environmental tests, chronologically reported in Table 2, were carried on the device D2.

Table 1 Life tests

Table 2 Environmental tests on D2