A laser pump-re-pump atomic magnetometer

We demonstrate experimentally an atomic magnetometer based on optical pumping theory, a magnetic resonance that is induced by a radio frequency field and dependent on the magnetic field strength. Compared with the conventional method using one radiation field, which is used not only as the probe beam but also as a pump beam, the additional re-pump beam can increase remarkably the amplitude of the signal. It is shown that the amplitude of the magnetic field resonance signal can increase more than 55% by using an additional re-pump beam, which makes the sensitivity of the magnetometer higher. Finally, we investigate the relation between amplitude of the signal and re-pump laser power, and calculate the atomic population in the trapping states with rate equations.

Theoretical Calculations and Experimental Verification for the Pumping Effect Caused by the Dynamic Micro-tapered Angle

The atomizer with micro cone apertures has advantages of ultra-fine atomized droplets, low power consumption and low temperature rise. The current research of this kind of atomizer mainly focuses on the performance and its application while there is less research of the principle of the atomization. Under the analysis of the dispenser and its micro-tapered aperture＇s deformation, the volume changes during the deformation and vibration of the micro-tapered aperture on the dispenser are calculated by coordinate transformation. Based on the characters of the flow resistance in a cone aperture, it is found that the dynamic cone angle results from periodical changes of the volume of the micro-tapered aperture of the atomizer and this change drives one-way flows. Besides, an experimental atomization platform is established to measure the atomization rates with different resonance frequencies of the cone aperture atomizer. The atomization performances of cone aperture and straight aperture atomizers are also measured. The experimental results show the existence of the pumping effect of the dynamic tapered angle. This effect is usually observed in industries that require low dispersion and micro- and nanoscale grain sizes, such as during production of high-pressure nozzles and inhalation therapy. Strategies to minimize the pumping effect of the dynamic cone angle or improve future designs are important concerns. This research proposes that dynamic micro-tapered angle is an important cause of atomization of the atomizer with micro cone apertures.

State Preparation in a Cold Atom Clock by Optical Pumping

We implement optical pumping to prepare cold atoms in our prototype of the ST Rb space cold atom clock, which operates in the one-way mode. Several modifications are made on our previous physical and optical system. The effective atomic signal in the top detection zone is increased to 2.5 times with 87% pumping efficiency. The temperature of the cold atom cloud is increased by 1.4 μK. We study the dependences of the effective signal gain and pumping efficiency on the pumping laser intensity and detuning. The effects of σ transition are discussed. This technique may be used in the future space cold atom clocks.

A 795 nm gain coupled distributed feedback semiconductor laser based on tilted waveguides

The 795 nm distributed feedback lasers have great application in pumping the Rb D1 transition.In this paper,in order to realize specific 795 nm lasing,we designed tilted ridge distributed feedback lasers based on purely gain coupled effect induced by periodic current injection windows through changing the angle of the tilted ridge.The fabricated devices were cleaved into 2 mm-cavity-length,including 5 tilted angles.The peak output powers of all devices were above 30 mW.Single longitudinal mode lasing was realized in all tilted Fabry-Perot cavities using periodic current injection windows,with side mode suppression ratio over 30 dB.The total wavelength range covered 8.656 nm at 20℃.It was disclosed theoretically and experimentally that the output powers,threshold currents,and central wavelengths of the tilted ridge purely gain coupled DFB lasers were relevant to the tilted angles.The results will be instructive for future design of DFB laser arrays with different central wavelengths.