Two methods for polarization stabilization of an internal-mirror 3.39-µm He—Ne laser are reported. The first relies on a concurrently lasing 1.15-µm transition by fixing the relative amplitude of two orthogonally polarized longitudinal modes that are split by a Rochon prism and detected with separate Si photodiodes. In the second method, two spatially separated orthogonally polarized adjacent 3.39-µm modes are optically balanced, differentially chopped, and recombined on a single InSb photodiode for phase-sensitive detection. The dual-wavelength scheme has been tested by beating against a methane-stabilized 3.39-µm He-Ne laser, which yields maximum excursions of < 0.5 MHz over several hours and comparable reproducibility. The polarization-stabilized He—Ne laser has been used as a reference for a tunable color-center laser molecular-beam optothermal spectrometer and provides a precision of better than 2 MHz.
© 1992 Optical Society of America
M-L. Junttila and A. S. Pine, "Polarization-stabilized 1.15- and 3.39-µm He—Ne lasers," Appl. Opt. 31, 5034-5037 (1992)