High resolution VUV spectroscopy of hydrogen
To allow spectroscopy of atomic hydrogen, a source of Lyman-alpha radiation
(wavelength 121.56 nm, resonant with th 1S-2P transition in hydrogen) is
needed that is both powerful and narrowband .
This radiation is produced in five steps:
i) narrowband cw light source, tunable around at 730 nm (6 time the
Lyman alpha wavelength).
This source is a Ar+ pumped Ti:Saff laser
ii) pulsed amplification in an excimer-pumped dye amplifier.
iii) frequency doubling to 365 nm in a KDP crystal
iv) post amplificatyion i a single excimer pumped UV dye amplifier stage
v) third-harmonic generation in a phase matched mixture of krypon and argon
The above scheme leads to tunable light with a band width of about 200 MHz,
only slightly larger than the natural linewidth (100 MHz) of the 1S-2P transition
In 1999 we launched a project aiming at improving the bandwidth. The essence
of this method is described briefly below.
Frequency doubling of pulsed light inside a cavity.
We are investigating the possiblity to imporve the bandwidth of the above
scheme by perferming the second and third harmonic generation inside cavities
with sufficiently high finnesse. To this end a cavity is kept at resonance
using a reference beam and pulsed light of the same frequency is then coupled
A new method was devised in which a pulse of light could be captured in a
cavity with essentially 100 % efficiency . We used an input coupler with
. O.J. Luiten, H.G.C. Werij, I.D. Setija, M.W. Reynolds, T.W. Hijmans,
and J.T.M. Walraven,
Lyman-alpha Spectroscopy of Magnetically Trapped Atomic Hydrogen,
Phys. Rev. Lett. 70, 554-557 (1993).
. B.P.J. Bret, T.L. Sonnemans, and T.W. Hijmans, Capturing a light
pulse in a short high-finnesse cavity, submitted to Phys. Rev. A.