EGAS41 - Swansea University
EGAS41 - Swansea University
EGAS41 - Swansea University
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41 st EGAS CP 39 Gdańsk 2009<br />
Non-linear magneto-optical resonances and cascade coherence<br />
transfer at 6S 1/2 → 7P 3/2 excitation of cesium<br />
A. Atvars, M. Auzinsh, R. Ferber, F. Gahbauer, A. Jarmola ∗<br />
Laser Centre, <strong>University</strong> of Latvia, 19 Rainis Blvd., LV-1586 Riga, Latvia<br />
∗ Corresponding author: jarmola@latnet.lv<br />
Non-linear magneto-optical resonances have been studied experimentally and theoretically<br />
at 6S 1/2 → 7P 3/2 excitation of atomic cesium. Unlike in previous studies (see, for example,<br />
[1] and references therein), we have observed the resonances in laser induced fluorescence<br />
(LIF) from the 7P 3/2 state as well as from intermediate states 6P 1/2 and 6P 3/2 that were<br />
populated by cascades (see. Fig. 1(a)). The experiment was performed with cesium<br />
vapor in a sealed glass cell at a room temperature. A three-axis Helmholtz coil system<br />
compensated the ambient magnetic field and scanned the magnetic field in the observation<br />
direction. Cesium atoms were excited to the 7P 3/2 state by linearly polarized laser<br />
radiation at 455.5 nm with its polarization vector perpendicular to the scanned magnetic<br />
field. Three interference filters were used to select different transitions for observation.<br />
The two orthogonal LIF polarization components (parallel I par and perpendicular I per to<br />
the laser polarization direction) were detected simultaneously with photodiodes while the<br />
magnetic field was scanned. Figure 1(b) shows the dependence of the polarization degree<br />
on the magnetic field observed in the fluorescence to the ground state from two different<br />
states, 7P 3/2 and 6P 3/2 , when the original excitation took place from two different hyperfine<br />
levels of the ground state to the 7P 3/2 state. Work is in progress to describe the<br />
signals with a detailed theoretical model based on the optical Bloch equations.<br />
(a)<br />
6P 1/2<br />
D 1<br />
D 2<br />
6S 1/2<br />
Fg = 4<br />
Fg = 3<br />
9192.6 MHz<br />
7P 3/2<br />
7S 1/2<br />
5D 5/2<br />
455.5 nm<br />
894 nm<br />
852 nm<br />
6P 3/2<br />
5D 3/2<br />
(I par<br />
-I per<br />
)/(I par<br />
+I per<br />
)<br />
0,16<br />
0,14<br />
0,12<br />
0,10<br />
0,08<br />
0,06<br />
0,04<br />
0,02<br />
0,00<br />
Excitation (455nm):<br />
Cs 6S 1/2<br />
7P 3/2<br />
(b)<br />
Obs.: D 2<br />
(F g<br />
= 4)<br />
I = 1200 mW/cm 2<br />
S = 3.2 mm 2<br />
Obs.: 455nm (F g<br />
= 4)<br />
Obs.: 455nm (F g<br />
= 3)<br />
Obs.: D 2<br />
(F g<br />
= 3)<br />
-6 -4 -2 0 2 4 6<br />
Magnetic field, G<br />
Figure 1: (a) Energy levels of 133 Cs, (b) polarization degree vs. magnetic field.<br />
Acknowledgment<br />
We acknowledge support from the Latvian National Research Programme in Material Sciences<br />
Grant No. 1-23/50 and the LZP Grant No. 09.1196.<br />
References<br />
[1] M. Auzinsh, R. Ferber, F. Gahbauer, A. Jarmola, L. Kalvans, Phys. Rev. A 78,<br />
013417 (2008), arXiv:0803.0201.<br />
99
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