Gas-discharge laser on a self-terminating thallium transition

We report an experimental study of the performance parameters of a gas discharge pumped thallium vapour laser operating on the 7s²S_1/2 — 6p²P_3/2^o self-terminating transition at 535 nm. The switch we used, a TPI3-10k/25 cold-cathode thyratron, ensures a rise time of the load voltage pulse less than 15 ns. The laser output power is shown to increase in proportion to the energy stored in the discharge capacitor (up to the maximum voltage of the thyratron). The optimal pump pulse repetition rate for He(Ne) — Tl mixtures is ~1.75 kHz. Even small hydrogen additions reduce the lasing energy and average output power. The addition of bismuth vapour increases the optimal pulse repetition rate (up to 3 kHz) and average output power. The factors responsible for the lower lasing efficiency in comparison with the copper vapour laser are analysed.