We have demonstrated a pulsed two-photon laser at the transition $3d{}_{}{}^2{}_{}{}^{}D-2s{}_{}{}^2{}_{}{}^{}S$ of atomic Li (frequency ${\omega }_{31}$) by (i) generation of a coherent light beam at ${\omega }_x$, stimulated by light pulses at ${\omega }_1={\omega }_{31}-{\omega }_x$, and (ii) single-pass amplification of injected light at ${\omega }_3=\frac{{\omega }_{31}}{2}$.

• Received 20 May 1981

DOI:https://doi.org/10.1103/PhysRevLett.47.171