High-energy mid-infrared intrapulse difference-frequency generation with 5.3% conversion efficiency driven at 3 µm.

Area of Science:

• Nonlinear Optics
• Quantum Electronics
• Laser Physics

Background:

• Intrapulse difference-frequency generation (IPDFG) is a method for producing few-cycle mid-infrared (MIR) radiation.
• Improving IPDFG conversion efficiency is crucial for practical applications, with longer driving wavelengths potentially reducing quantum defects.

Purpose of the Study:

• To report a high-energy MIR IPDFG source.
• To achieve a record-high conversion efficiency for MIR generation.
• To utilize the generated MIR pulses for subsequent supercontinuum generation.

Main Methods:

• Utilized 3 µm, 35 fs, 10 kHz driving pulses for intrapulse difference-frequency generation.
• Characterized the generated MIR output, including spectral range, pulse energy, average power, and pulse width.
• Employed a KRS-5 crystal to generate a supercontinuum from the high-energy MIR pulses.

Main Results:

• Achieved a record conversion efficiency of up to 5.3% for MIR IPDFG.
• Generated MIR pulses with 5 µJ energy, 50 mW average power, spanning 6–13.2 µm.
• Produced a 3-octave supercontinuum (2–16 µm) with 2.4 µJ pulse energy and 24 mW average power.

Conclusions:

• Demonstrated a high-performance MIR IPDFG source with unprecedented conversion efficiency.
• The generated few-cycle MIR pulses are suitable for driving broadband supercontinuum generation.
• This work advances MIR generation capabilities for spectroscopy and other applications.