4He optical pumping with polarization modulated light

Harald Klepel, Dieter Suter

George M. Keiser, H. G. Robinson, C.E. Johnson

H. Gilles, Bernard Cheron, J. Hamel

In optical pumping experiments using a laser, beam polarization can be modulated with the help of an electrooptic modulator device. This technique has been applied to pump 4He(23S1) metastable atoms. New resonances, never observed before, has been studied theoretically and experimentally versus geometric and modulation parameters and an application to high sensitivity magnetometer is presented.

Bernard Cheron, H. Gilles, J. Hamel +2 more

Recently a distributed Bragg reflection (DBR) laser diode was commercialised by SDL (USA) for helium optical pumping experiments. An interesting feature of the new device is the possibility of frequency modulation of the diode output by modulating the current intensity, leading to a new pumping scheme called optical pumping with frequency modulated light. We develop this method to induce spin precession and obtain new resonances in 4He atomic gas, simply by modulating the frequency of the pumping light at the Larmor frequency of atomic states in a static magnetic field. These resonances are analysed with a simple model taking into account velocity changing collisions.

高啓 久保, 清人 大川

A. Cassimi, Bernard Cheron, J. Hamel

$^4$He (2 $^3$S$_1$) metastable atoms are optically pumped with intensity modulated light. The use of a single mode diode-pumped LNA laser as the pumping source, allows the study of resonance signals predicted by the optical pumping theory but not yet observed. Resonances are detected on the transmitted pumping beam at the modulation frequency and its harmonics. Application of this method to high sensitivity magnetometers is suggested.