THE RESULTS OF LASING LINEWIDTH NARROWING ON THE VEPP-3 STORAGE RING OPTICAL KLYSTRON

Lasing in visible and ultraviolet ranges was obtained using the optical klystron installed on VEPP-3 storage ring in 1988 [I.B. Drobyazko et al., Nucl. Instr. and Meth. A282 (1989) 424] with minimum relative linewidth DELTA-lambda/lambda = 10(-4). To decrease the linewidth we have performed the following experiments. The optical cavity of the VEPP-3 storage ring optical klystron has been updated to install intracavity selective elements. We used the simplest selective element - a glass plate with parallel faces as a natural interferometer. Using a 1.2 mm thick glass plate installed inside the optical cavity we have reached lasing with a very narrow linewidth. The minimum relative lasing linewidth, 2.7 x 10(-6) (lambda = 6250 angstrom, DELTA-lambda = 0.017 angstrom), was 30 times narrower than the minimum one without the plate (DELTA-lambda = 0.6 angstrom). The average power was the same in both cases. Experiments on lasing linewidth narrowing with the use of the plates with different thickness are under way.