Nanosecond 389-nm coherent light source with injection seeding for nuclear spin polarization of 3He atoms

We have developed a 389-nm frequency-doubled nanosecond-pulsed coherent light source with injection seeding for nuclear polarization of 3He atoms with 23S→33P and then suggested four kinds of spectroscopic methods with the injection-seeded light source. With this light source, we have conducted saturated absorption spectroscopy of metastable 3He atoms. As a result, an accurate resonance frequency of 770682 GHz and a dip width of 1.7 GHz of metastable 3He atoms are obtained. Therefore, the linewidth of our injection-seeded light source can be estimated at 65 MHz or 1.7 GHz. Our light source has potential for the polarization of 3He due to high-peak power and narrow linewidth of the injection-seeded light source.