High-resolution dual comb spectroscopy using a free-running, bidirectional ring titanium sapphire laser

Area of Science:

• Spectroscopy
• Laser Physics
• Molecular Physics

Background:

• Dual-comb spectroscopy (DCS) is a powerful technique for high-resolution molecular analysis.
• Achieving sufficient coherence in DCS typically requires complex stabilization or post-processing.
• Ti:sapphire lasers offer broad spectral coverage and high peak powers, making them attractive for DCS.

Purpose of the Study:

• To demonstrate resolved molecular absorption lines using DCS with a bidirectional Ti:sapphire laser.
• To investigate the coherence properties of a bidirectional laser cavity for DCS applications.
• To explore the potential of this method for future applications like atmospheric remote-sensing.

Main Methods:

• Utilized a Kerr-lens mode-locked bidirectional Ti:sapphire ring laser cavity.
• Employed two free-running 100 fs Ti:sapphire pulse trains for DCS.
• Recorded a 3 nm broad spectrum in 5.3 ms with ≈ 1 GHz spectral resolution.

Main Results:

• Successfully measured resolved molecular absorption lines in the oxygen A-band (760 nm).
• Achieved high spectral resolution (≈ 1 GHz) without active phase stabilization or post-processing corrections.
• Demonstrated sufficient absolute and mutual coherence from the bidirectional laser configuration for DCS.

Conclusions:

• The bidirectional laser configuration provides adequate coherence for DCS of resolved molecular absorption lines.
• This approach simplifies DCS setup by eliminating the need for active stabilization.
• The results pave the way for DCS in the UV range and extend its applicability for atmospheric remote-sensing.