Research On Laser Frequency Control For Interferometry Gyroscope

Cold atom interferometers are widely used in fundamental physical research and precision experiments. Therefore, it has excited world-wide interests in developing high precision atom interferometer.In atom interferometry gyroscope, several pulses of couter-propagating laser beams are applied to the atoms to induce the stimulated Raman transitions between the two hyperfine ground states of atoms. Since phase noise between the two beams is directly introduced to the interference phase shift during the stimulated Raman transitions, a pair of lasers with low phase noise is required to increase the sensitivity of the atom interferometer. The optical phase locking of two lasers with an electronic servo loop is used for making phase coherent lasers. We achieve the residual phase noise of two phase-locked lasers of below-95 d Bc/Hz in the offset frequency range of 1k Hz~100k Hz, this phase noise is not the limit of our present measurement sensitivity.It is critical to prepare ultra-cold atom fountain first for the precision rotation measurement. In order to improve the quality of the atom fountain, we have designed a Frequency Voltage Converter(FVC) for the laser frequency control of an atom interferometer. During the cooling and trapping stage, the frequency of cooling laser is stabilized within 1MHz by frequency locking on reference laser with tunable offset using FVC. The offset voltage of FVC is changed to control the cooling frequency shift during moving molasses stage, and the maximum shift of frequency is about 120 MHz within 0.8ms, which can meet our requirement for detuning in moving molasses.