Dimer laser

By optical excitation with argon and krypton laser lines, continuous laser oscillation on A -> X and B -> X transitions of Li Na2 and K molecules can be achieved dimer lasers show such interesting features as multiline emission, extremely low threshold pump intensities and forward-backward amplification asymmetry. Basic principles, operating conditions and applications of these lasers will be discussed. The dimer lasers operate between bound electronic states, resulting in the emission of discrete lines. To achieve tunable laser oscillation, continuous emission bands from bound-free transitions have to be considered. Some possibilities for alkali dimers are outlined and recent spectroscopic investigations on UV excited diffuse bands are reported. 

Up to now/ the dimer laser system has been described alone in terms of population inversion between suitable energy levels/ and for this description the condition S2 > A 2 is indeed the only necessary condition for cw laser oscillation/ as long as the thermal population density in the lower laser level remains negligibly low. However/ as this optically pumped laser system is a coherently excited three level system/ the coherent emission can also be described as stimulated Raman scattering/ which is resonantly enhanced by the common level 3 of the pump and laser transitions. This coupled two photon or Raman process does not require a population inversion between levels 3 and 2 and introduces qualitatively new aspects which appreciably influence and change the normal laser behaviour. For a detailed and deeper description of the coherently excited three level dimer... 

Figure 4. Multiline laser spectrum of Na dimer laser on B Uu transitions, excited by...

Figure 11. Relative forward amplification profiles for different dimer laser intensities li and fixed pump intensity Ip.

Physical Studies of Optically Pumped Dimer Lasers... 

We report on saturated absorption experiments in Na2> realized with a tunable and stabilized argon laser. These experiments provide both spectroscopic and physical results, which help in understanding the behavior of optically pumped alkali dimer lasers. We briefly describe a new double resonance experiment which enables us to study the gain line-shapes of the dimer laser and to demonstrate the backward-forward gain competition. 

Table I. Coincidences between transitions in the B liy-X Tg Systems of Na2 and Li2 and argon laser lines. Dimer laser emission has been observed from all the underlined transitions. The accuracy is 5 x lO" A for all resolved lines. A is the difference in A between measured vacuum wavelength and the calculated wavelength from the constants of References 6 and 7.

Fig. 8.32 Selective pumping of a high vibrational level (u, 7) by stimulated emission pumping in Na2 with a Na2 dimer laser (a) level scheme (b) experimental realization [1081]...

B. WeUegehausen, Optically pumped CW dimer lasers. IEEE J. Quantum Electron. 15, 1108(1979)... 

B. Heymen, C. Liedenbaum, S. Stolte, and J. Reuss, Hole burning in the IR predissociation spectrum of SFe-dimers, Laser Chem. 8 275 (1988). 

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