Efficient half-harmonic generation of three-optical-cycle mid-IR frequency comb around 4 µm using OP-GaP

Area of Science:

• Quantum Optics
• Nonlinear Optics
• Materials Science

Background:

• Frequency combs are crucial for precise measurements.
• Mid-infrared (mid-IR) light sources are important for spectroscopy and sensing.
• Generating short pulses in the mid-IR is challenging.

Purpose of the Study:

• To demonstrate a broadband mid-infrared frequency comb.
• To investigate half-harmonic generation (HHG) using orientation-patterned gallium phosphide (OP-GaP).
• To compare OP-GaP with other nonlinear materials for this application.

Main Methods:

• Broadband mid-infrared frequency comb generation via HHG.
• Utilizing orientation-patterned gallium phosphide (OP-GaP) as the nonlinear medium.
• Experimental comparison of OP-GaP with gallium arsenide (GaAs) and lithium niobate (LiNbO3).

Main Results:

• Achieved a broadband mid-IR frequency comb centered at 4.2 µm with a three-optical-cycle pulse duration.
• Obtained a ~43% conversion efficiency using OP-GaP.
• OP-GaP demonstrated superior performance, yielding shorter pulses and higher efficiency compared to GaAs and LiNbO3.

Conclusions:

• Orientation-patterned gallium phosphide is highly effective for mid-infrared frequency comb generation.
• HHG is a promising technique for creating short-pulse, intrinsically-locked frequency combs.
• This work enables future development of advanced mid-IR frequency comb sources.