Longitudinal mode selection by injection in a high pressure CO(2) laser

Area of Science:

• Optics and Photonics
• Laser Physics
• Molecular Spectroscopy

Background:

• High-pressure carbon dioxide (CO(2)) lasers are valuable sources for various applications.
• Achieving single longitudinal mode (SLM) operation is crucial for many laser applications requiring high spectral purity.
• Existing methods for SLM selection in CO(2) lasers can be complex or limited in tunability.

Purpose of the Study:

• To investigate and achieve single longitudinal mode (SLM) selection in a 10-atm CO(2) laser.
• To develop a simple analytical formula for predicting the minimum injection intensity required for SLM operation.
• To explore the potential for continuously tunable SLM operation in high-pressure CO(2) lasers.

Main Methods:

• Experimental investigation of SLM selection using continuous-wave (cw) and pulsed injection seeding.
• Development of an analytical formula relating required injection intensity to frequency detuning and cavity mode detuning.
• Comparison of the derived formula with experimental results from TEA (Transversely Excited Atmospheric) lasers.

Main Results:

• Successful demonstration of SLM selection in a 10-atm CO(2) laser with low-power injection.
• Derivation of a simple analytical formula accurately predicting the minimum injection intensity.
• The formula shows strong dependence on detuning from the gain curve center and nearest cavity mode.

Conclusions:

• The developed formula provides a reliable tool for predicting SLM selection conditions.
• The findings indicate the possibility of continuously tunable SLM operation in high-pressure CO(2) lasers with minimal optical elements.
• The study reviews suitable injection sources for achieving efficient SLM selection.