Characteristics of laser emission and gain on competing transitions in an sr⁺ recombination laser

Laser action at 416.2 nm as well as 430.5 nm was investigated in a low-repetition-rate strontium-ion recombination laser incorporating a dispersive cavity. At best 35% of the pulse energy at 430.5 nm was available at 416.2 nm and the temporal width of the 416.2 nm laser emission was 10 to 100 ns (fwhm) shorter than that at 430.5 nm. Peak axial small-signal gains were also measured for both transitions. The optimum small-signal gain at 430.5 nm was 8.3% cm^-1 while the small-signal gain at 416.2 nm ranged from 1 to 2% cm^-1 over a variety of discharge conditions. It is concluded that the ratios of gain and pulse energy at 430.5 nm to that at 416.2 nm imply partial electron collisional mixing between the lower laser levels Sr II 5²P_3/2 and 5²P_1/2.