Anti-Stokes Raman laser

The first observation of nonresonant, stimulated anti-Stokes Raman emission is reported. A metastable $\mathrm{Tl}\left(6p{}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^o{}_{}{}^{}\right)$ inversion is created by selective photodissociation of TlCl. Raman scattering from the Tl metastable state to ground using 532- and 355-nm pump lasers resulted in stimulated emission at 376 and 278 nm, respectively. Conversion efficiencies up to 10% are reported.