The experiment requires four lasers in the UV spectral range. Specifically, we need the laser radiation at the wavelength listed in the table. Along with the wavelength, you also find the type of laser used as well as some details on the specs of the systems.
Wavelength | Usage | Type | Non-Linear Conv. | Pulse Length | Energy | fund. Linewidth | Remark |
---|---|---|---|---|---|---|---|
266 nm | Excitation of Dimer | Alexandrite | Third-Harmonic | 120 ns | 1 mJ | 8 MHz | tunable, injection seeded |
355 nm | Dissociation of Dimer | Ti:Sapphire | Second-Harmonic | 8 ns | 1 mJ | 100 MHz | tunable. injection seeded |
253.7 nm | Spin Selection | Ti:Sapphire | Third-Harmonic | 8 ns | > 200 muJ | < 100 MHz | regenerative amplifier, timing critical |
197.3 nm | Photo-Ionization | Ti:Sapphire | Fourth-Harmonic | 8 ns | >60 muJ | < 100 MHz | regenerative amplifier, timing critical |
The most stringent requirements have to be fulfilled by the Alexandrite and the Ti:Sapphire laser systems.
- The Alexandrite laser is used to spectroscopically select only dimer within a very narrow velocity window. This increases the propability of finding both Hg atoms of one pair in the detectors. Therefore, the Alexandrite laser has to have a very narrow frequency distribution, which requires long pulses. We opted for the Alexandrite laser since it shows long laser pulses. We have successfully reduced the linewidth of our laser to < 8 MHz (see this paper).
- A highly efficient spin analysis is necessary in order to close the loopholes associated with previous experiments. Simulations show that this is only possible if the two laser pulse arrive within a very narrow timing window, i.e. 2 nanoseconds with respect to each other. Therefore we decided to run a flashlamp pumped Ti:Sapphire laser simultaneously on two wavelengths. The exact timing is achieved using an optical delay line (see this paper or this one).
Prof. Dr. Thomas Walther
Laser und Quantenoptik
Institut für Angewandte Physik
Fachbereich 05 - Physik
Technische Universität Darmstadt
Schlossgartenstr. 7
D-64289 Darmstadt
+49 6151 16-20831 (Sekretariat)
+49 6151 16-20834 (Fax)
Thomas.Walther@physik.tu-...
03.04.19