EGAS41 - Swansea University

41 st EGAS CP 27 Gdańsk 2009
A 465 nm laser, based on sum frequency mixing in PP-KTP,
for investigations on metastable 3 He 2 * molecules
B. G̷lowacz 1,2,∗ , G. Tastevin 2 , P.J. Nacher 2
1 Atomic Optics Department, Jagiellonian University,
ul. Reymonta 4, 30-059 Kraków, Poland
2 Laboratoire Kastler Brossel, 24, rue Lhomond, 75005 Paris, France
∗ Corresponding author: glowacz@lkb.ens.fr
A single-frequency tunable laser has been developed to probe the 465 nm molecular absorption
lines of helium plasmas [1] in order to study the influence of helium metastable
molecules (He 2 *) on metastability-exchange optical pumping of 3 He [2] under various conditions
[3]. The generation of blue light is based on sum frequency mixing of two infra-red
laser beams at 923 nm and 937 nm (from 100 mW DFB laser diodes) in a non-linear PP-
KTP crystal. The overlapping of the IR beams in the crystal is obtained using a set of 3
dispersive prisms. A conversion efficiency of 2.9 % W −1 cm −1 is achieved, with a maximum
output power of 175 µW of blue a in single-pass configuration of pump beams through
the crystal. The specified range for temperature control of the IR laser diodes provides
a tuning range of 1.3 nm around the central wavelength 465.4 nm. It is thus possible to
probe the electronic transitions for branches Q(1-8), P(2) and R(0) of metastable 3 He 2 *
molecules.
References
[1] G.H. Dieke, Eugene Sant Robinson, Phys. Rev. 80, 1-5 (1950)
[2] P.J. Nacher, M. Leduc, J. Physique 46, 2057-2073 (1985)
[3] A. Nikiel et al., Eur. Phys. J Special Topics 144, 255-263, (2007)
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