Resonant sum and difference frequency mixing in Hg

Coherent tunable VUV radiation of narrow spectral width is generated by two-photon resonant sum and difference frequency mixing
(\omega_{vuv}^{\pm} = 2\omega_{uv} \pm \omega_{D})
of pulsed dye laser radiation in Hg vapor. The UV frequency ω
uv
is tuned to the two-photon resonances 6
¹
S
0
- 7
¹
S
0
(
\lambda_{uv} = 3127.6
Å), 6
¹
S
0
-6
¹
D
2
(
\lambda_{uv} = 2802.9
Å), and 6
¹
S
0
- 7
¹
D
2
(
\lambda_{uv} = 2594.5
Å). A second dye laser produces tunable radiation at ω
D
(
\lambda_{D} = 4200-6700
Å). At input powers of 1-2 MW, the different conversion schemes generate VUV light pulses of typically 0.5-3 kW in spectral regions between 1090 and 1960 Å. The experimental results provide information on the wavelength dependence of the generated VUV output, on the conversion efficiency, the phase-matching conditions, and on conversion limiting saturation phenomena. Besides the resonant frequency conversion, nonresonant frequency tripling and mixing is investigated at
\lambda_{vuv} = 1800-1880
Å in the vicinity of the resonance transition 6
¹
S
0
-6
¹
P
1
(
\lambda = 1849.5
Å).