EGAS41 - Swansea University

41 st EGAS CP 165 Gdańsk 2009
A coupled dark state magnetometer
L. Windholz 1 , W. Magnes 2 , A. Pollinger 2 , M. Ellmeier 1 , R. Lammegger 1,∗
1 Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010 Graz,
Austria
2 Space Research Institute of the Austrian Academy of Sciences, Schmiedlstrasse 6, 8042 Graz,
Austria
∗ Corresponding author: roland.lammegger@tugraz.at
Measuring magnetic fields by means of spectroscopic-optical methods has advantages
in many respects. E.g. in best case the magnetic field sensor of an optical magnetometer
can only be made of a (nonmagnetic) glass cell containing a tiny amount of an alkali
metal non perturbing the external magnetic field. Moreover, the optical sensor is working
near room temperature. Thus unlike to the (in common more sensitive) superconducting
quantum interference device (SQUID) magnetometer an extensive cooling down to
cryogenic temperatures can be avoided.
We consider a compact vertical surface emitting laser (VCSEL) based coupled dark
state magnetometer (CDSM). In such kind of optical scalar magnetometer the zeeman
split (magnetic sensitive) components of the coherent population trapping (CPT) resonance
spectrum are coupled by a multi chromatic light field. The resulting CDSMresonance
is used to determine an external magnetic field. Thus, by applying the Breit-
Rabi formula the scalar value of the external magnetic field can be derived directly from
the frequency of the magnetic sensitive CDSM-resonance signal.
In our investigations the advantages and constraints of such a compact magnetometer
type in terms of sensitivity, measurement bandwidth, noise and influence of magnetic field
gradients are outlined.
Acknowledgment
The work is founded by the Fonds zur Förderung der wissenschaftlichen Forschung (FWF)
(Project No.: L300-N02).
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