Feed-forward comb-assisted coherence transfer to a widely tunable DFB diode laser

Area of Science:

• Laser Physics
• Spectroscopy
• Optical Metrology

Background:

• Precise frequency control of lasers is crucial for high-resolution spectroscopy.
• Transferring phase coherence between lasers is challenging, especially over large frequency gaps.
• Existing methods often rely on phase-locked loops, limiting scanning capabilities.

Purpose of the Study:

• To develop a novel scheme for transferring phase coherence from a master laser to a slave laser.
• To enable continuous scanning across the slave laser's tuning range with absolute frequency determination.
• To achieve high injection efficiency into an optical cavity for sensitive spectroscopy.

Main Methods:

• Utilizing an optical frequency comb as a transfer oscillator.
• Implementing a high-bandwidth feed-forward control system without phase-locked loops.
• Employing a dual-parallel Mach-Zehnder interferometer as an optical single-sideband modulator.

Main Results:

• Successful coherence transfer across a 14 THz frequency gap.
• Achieved an approximately 10 kHz linewidth for the slave laser.
• Demonstrated high injection efficiency into an optical cavity with a finesse of 250,000.
• Obtained a cavity ring-down absorption spectrum of low-pressure ambient air over a 300 GHz window.

Conclusions:

• The new scheme effectively transfers phase coherence, enabling precise laser frequency control.
• The method allows for broad spectral scanning and absolute frequency determination.
• This technique significantly enhances capabilities for high-resolution spectroscopy, as demonstrated by ambient air analysis.