Intra-oscillator broadband THz generation in a compact ultrafast diode-pumped solid-state laser

Area of Science:

• Optics and Photonics
• Solid-State Physics
• Terahertz Science

Background:

• Terahertz (THz) radiation offers unique capabilities for spectroscopy and imaging.
• Generating powerful and broadband THz sources efficiently remains a challenge.
• Existing THz sources often suffer from large footprints, complexity, and high costs.

Purpose of the Study:

• To demonstrate a compact, single-stage THz source.
• To achieve broadband THz generation at megahertz repetition rates.
• To explore the potential of intra-oscillator optical rectification in gallium phosphide.

Main Methods:

• Intra-oscillator optical rectification (OR) within a laser cavity.
• Utilizing gallium phosphide (GaP) as the nonlinear optical material.
• Employing a Kerr-lens mode-locked ultrafast diode-pumped solid-state laser (DPSSL) oscillator.

Main Results:

• Generated broadband THz radiation up to 5.5 THz with 150 µW power using 105 fs pulses.
• Achieved up to 7 THz bandwidth with sub-50 fs pulses in a thinner GaP crystal.
• Operated at a megahertz repetition rate (∼80 MHz) with low diode-pump power (7 W).

Conclusions:

• Intra-oscillator OR in GaP offers a scalable pathway for powerful broadband THz generation.
• The demonstrated source is compact, cost-effective, and suitable for THz time-domain spectroscopy and imaging.
• This approach significantly reduces the footprint and complexity of THz sources.