Polarization-stabilized 1.15- and 3.39-microm He-Ne lasers

Area of Science:

• Laser Physics
• Spectroscopy
• Optical Engineering

Background:

• Stabilizing laser polarization is critical for high-precision measurements.
• Helium-Neon (He-Ne) lasers are widely used but require polarization control for specific applications.
• Existing methods may have limitations in stability and reproducibility.

Purpose of the Study:

• To develop and report two novel methods for polarization stabilization of an internal-mirror 3.39-micrometer He-Ne laser.
• To evaluate the performance and reproducibility of the developed stabilization techniques.
• To demonstrate the utility of the polarization-stabilized laser in a high-precision spectroscopic system.

Main Methods:

• Method 1: Utilizes a concurrently lasing 1.15-micrometer transition, fixing the relative amplitude of two orthogonally polarized modes split by a Rochon prism and detected by Si photodiodes.
• Method 2: Employs optical balancing of two spatially separated, orthogonally polarized 3.39-micrometer modes, followed by differential chopping and phase-sensitive detection using an InSb photodiode.
• Dual-wavelength scheme tested against a methane-stabilized 3.39-micrometer He-Ne laser.

Main Results:

• The dual-wavelength scheme demonstrated high stability, with frequency excursions of less than 0.5 MHz over several hours.
• Comparable reproducibility was achieved with the developed polarization stabilization methods.
• The polarization-stabilized He-Ne laser provided a precision better than 2 MHz when used as a reference.

Conclusions:

• Both reported methods effectively achieve polarization stabilization for a 3.39-micrometer He-Ne laser.
• The dual-wavelength approach offers excellent frequency stability and reproducibility.
• The polarization-stabilized laser serves as a valuable, high-precision reference for advanced spectroscopic instruments like tunable color-center laser molecular-beam optothermal spectrometers.