Ultrafast 1-GHz repetition rate dual-comb optical parametric oscillator

Area of Science:

• Laser Physics
• Spectroscopy
• Nonlinear Optics

Background:

• Femtosecond optical parametric oscillators (OPOs) are crucial for generating tunable ultrashort pulses.
• Dual-comb spectroscopy offers high resolution and broad spectral coverage but requires stable, synchronized sources.
• Achieving high repetition rates (1 GHz) in dual-comb systems is challenging.

Purpose of the Study:

• To demonstrate dual-comb operation from a femtosecond OPO at a 1-GHz pulse repetition rate.
• To develop a compact and stable dual-comb source for spectroscopic applications.
• To showcase the system's capability for fast and sensitive gas detection.

Main Methods:

• Utilized a singly-resonant OPO synchronously pumped by a Yb:CaF2 diode-pumped solid-state laser.
• Implemented a spatially multiplexed single-cavity configuration for both OPO and pump laser dual-comb generation.
• Achieved wavelength tunability from 1415-1645 nm (signal) and 2960-4085 nm (idler).

Main Results:

• First demonstration of dual-comb operation from a femtosecond OPO at 1 GHz.
• Achieved average powers up to 650 mW (signal) and 200 mW (idler) per comb.
• Delivered an instantaneous bandwidth of 2.5 THz with high power per comb line.
• Successfully detected ~2 ppm methane over 41 m with a normalized signal-to-noise ratio of 42.0 dB Hz^1/2 without active stabilization.

Conclusions:

• The developed dual-comb femtosecond OPO is a compact, stable, and powerful source.
• The system enables fast and highly sensitive dual-comb spectroscopy.
• Potential for various spectroscopic applications, including environmental monitoring.