New tunable laser sources for helium-3 and helium-4 optical pumping

Although tremendous effort has been put forth in the investigation and development of various types of lasers operating at 1083 nm for the optical pumping of the helium metastable states, most lasers heretofore have never operated at this wavelength without the insertion of various tuning elements.; We investigated several alternative laser sources to the Nd:LMA laser. First, we designed, built, and investigated several Nd:glass fiber laser systems capable of being tuned to the helium transitions. This research yielded a totally integrated fiber laser with an internal Bragg grating as a narrow band-width, tunable output coupler. The power output was near 10 mW and is applicable to helium magnetometers operating in remote environments.; Second, two new diode-pumped solid state laser systems tunable to the helium metastable transitions were developed. A Nd:CaYAlO{dollar}sb4{dollar} laser crystal was tuned to 1083 nm for the first time. The most promising solid state laser developed utilized a Nd:LuAlO{dollar}sb3{dollar} crystal. This crystal proved to be the first laser whose free-running output was at the helium wavelength. Furthermore, the crystal was pumped by a high-power, collimated, laser diode array and achieved 1.5 watts of output at 1083 nm. The crystal did not exhibit thermal lensing and is an alternative to Nd:LMA.