The results of lasing linewidth narrowing on VEPP-3 storage ring optical klystron

Lasing in the visible and ultraviolet ranges was reached in the optical klystron installed on a VEPP-3 storage ring (see N. A. Vinokurov et al., 1977) with minimum relative linewidth Δλ/λ = 10^-4. In order to decrease the linewidth the authors performed the experiments reported here. The optical cavity on VEPP-3 storage ring optical klystron was updated to install intracavity selective elements. The authors used the simplest selective element-a glass plate with parallel planes as a natural interferometer. With a 1.2 mm thick glass plate installed inside the optical cavity, lasing has been reached with a very narrow linewidth. The minimum relative lasing linewidth, 2.7×10^-6 (λ=6250 Å, Δλ=0.017 Å), was 30 times narrower than the minimum one without the plate (Δλ=0.6 Å). The average power was the same in both cases