Tunability characteristics of waveguide CO(2) lasers with internal etalons

Area of Science:

• Laser Physics
• Optical Engineering

Background:

• Waveguide carbon dioxide (CO2) lasers are crucial for various applications.
• Increasing the tuning range of these lasers enhances their versatility and performance.
• Intracavity etalons are used for axial mode selection, but can impact tuning range.

Purpose of the Study:

• To investigate methods for increasing the tuning range of waveguide CO2 lasers.
• To evaluate the effect of a longer discharge and a tilted intracavity etalon on laser tuning range.
• To analyze the influence of etalon material properties on performance.

Main Methods:

• Theoretical calculation of tuning range considering etalon losses.
• Modeling the tuning range as a function of laser gain, pressure, and discharge length.
• Comparing performance with and without mode selection, and with different etalon materials.

Main Results:

• The tuning range is significantly influenced by the etalon material's refractive index and absorptivity.
• Using a cadmium telluride (CdTe) etalon in a 25-cm laser increased tuning range from 1.5 GHz to 2.2 GHz.
• An air etalon resulted in reduced bandwidth due to higher tilting losses.

Conclusions:

• A longer discharge combined with a tilted intracavity etalon can effectively increase the tuning range of CO2 lasers.
• Cadmium telluride (CdTe) is a promising material for etalons to achieve wider tuning ranges.
• Careful selection of etalon material is critical to optimize laser performance and avoid bandwidth reduction.