Multifrequency emission from submillimeter lasers

Simultaneous stimulated emission at two submillimeter frequencies with parallel polarization was achieved for the first time in a waveguide electric-discharge HCN laser (λ₀ = 337 μ): higher modes (TE₀₁ + EH₂₁)_q and (TE₀₂ + EH₂₂)_{q – 1}, were generated in a resonator free of phase anisotropy. The frequency interval between these modes varied continuously from ~ 50 kHz to ~ 3 MHz. Moreover, simultaneous emission of two linearly polarized mutually orthogonal modes was observed for the first time in a waveguide HCN laser in which the exit mirror was in the form of two parallel wire gratings with orthogonal directions of the wires. Simultaneous emission of three frequencies was also observed for this laser.