Direct laser measurement of the Lamb shift of 23S-2(3)P transitions in helium

Single-frequency operation of a diode-pumped lanthanum-neodymium-hexaaluminate laser by using a twisted-mode cavity

Single-frequency operation of a diode-pumped lanthanum-neodymium-hexaaluminate laser using a twisted mode geometry is reported. Single-mode output without additional intracavity frequency-selective elements was observed. The laser was tunable from 1.054 to 1.059 microm and from 1.077 to 1.088 microm. A single-frequency output of 150 mW at 1.083 microm has been obtained. The laser is particularly interesting in relation to experiments that use metastable helium.

Tunable diode-laser-pumped solid state LNA laser for helium spectroscopic experiments

We have designed, built, and tested a compact, integrated, single-mode solid state LNA laser pumped by a semiconductor laser array for exciting the He resonance line at lambda = 1.083 microm. The laser's three major components are mounted on a single aluminum base, and the diode laser and its beam shaping optics are mounted on a separate stage. This compact and stable structure provides good frequency stability and nearly pure TEM(00) transverse mode operation. The laser can be tuned around the metastable He resonance transition in a single longitudinal mode with linewidth congruent with 5 MHz using a solid, 60% coated intracavity 0.25-mm thick etalon. Saturated absorption signals on this transition have been used to measure the stability and tuning range. We have measured the properties for several crystals and calculated the expected performance characteristics to compare with the measured ones.