Noise reduction in an argon laser with a phase-conjugating external cavity

Area of Science:

• Optics and Photonics
• Laser Physics

Background:

• Continuous-wave (cw) multilongitudinal mode argon (Ar(+)) lasers are crucial for various scientific applications.
• Improving the signal-to-noise ratio (SNR) is essential for high-precision laser measurements and experiments.
• Laser cavity design significantly impacts output stability and noise characteristics.

Purpose of the Study:

• To investigate the efficacy of reinjecting a fraction of the output beam back into the laser cavity to enhance SNR.
• To explore the use of an external cavity terminated by a phase-conjugate mirror for self-aligned coupled cavity formation.
• To quantify the noise reduction and spectral component attenuation achieved by the proposed method.

Main Methods:

• Coupling an argon laser to an external cavity.
• Terminating the external cavity with a phase-conjugate mirror to create a self-aligned coupled cavity.
• Reinjecting a small fraction of the laser's output beam back into the main cavity.

Main Results:

• Significant improvement in the signal-to-noise ratio (SNR) of the cw multilongitudinal mode Ar(+) laser.
• Reduction of low-frequency noise components by up to 15 dB.
• Attenuation of frequency components of longitudinal-mode beating spectrum by factors reaching 46 dB.

Conclusions:

• Reinjecting a fraction of the output beam into the laser cavity is an efficient method to improve SNR.
• The self-aligned coupled cavity configuration effectively reduces laser noise.
• This technique offers a practical approach to enhance the performance of Ar(+) lasers for demanding applications.