Continuous wave alexandrite laser pumped by novel mercury arc lamps

Alexandrite is a unique tunable solid state laser material which lases continuously with arc lamp pumping.1 However, a xenon arc lamp cannot give a large laser gain due to spectral mismatching. And, a high pressure mercury arc lamp, a more efficient pumping source, fluctuates seriously in dc operation due to vapor condensation. To solve these problems, we developed a stable fully vaporized mercury long arc lamp with sufficient vapor pressure for the purpose of alexandrite laser pumping. To achieve the stable arc in dc operation, we needed (1) a novel thermally insulated cathode and (2) fine adjustment of the mercury pressure.