HELIUM SPECTROSCOPY USING AN INGAAS LASER-DIODE

Absorption spectroscopy in He-3 and He-4 has been performed with an InGaAs single-mode distributed Bragg reflection laser diode. The laser source provides as much as 120 mW of single-mode, single-frequency output in the 1083-nm region of the spectrum. Frequency tuning of the laser diode output by means of the junction temperature allows for mode-hop-free scanning of the entire 2(3)S-2(3)P manifold in both the He-3 and He-4 absorption spectra. The authors believe this to be the first report of semiconductor laser spectroscopy at this wavelength. Such a device will have significant applications in optical pumping, atomic cooling and trapping, fundamental nuclear studies, magnetometry, and gas dynamics.