Difference frequency generation of 8-microm radiation in orientation- patterned GaAs

Area of Science:

• Optics and Photonics
• Materials Science
• Nonlinear Optics

Background:

• Mid-infrared (mid-IR) light sources are crucial for spectroscopy and sensing.
• Generating tunable, narrowband mid-IR light efficiently remains a challenge.
• Orientation-patterned semiconductors offer a promising route for nonlinear optical frequency conversion.

Purpose of the Study:

• To demonstrate first-order quasi-phase-matched difference frequency generation (DFG) in orientation-patterned gallium arsenide (GaAs).
• To achieve narrowband tunable mid-IR light generation.
• To assess the material uniformity and performance of the fabricated GaAs device.

Main Methods:

• Fabrication of an all-epitaxial orientation-patterned GaAs crystal using molecular beam epitaxy (MBE) and hydride vapor phase epitaxy (HVPE).
• Mixing of two infrared laser beams (1.3 µm and 1.55 µm) within the orientation-patterned GaAs crystal.
• Characterization of the generated idler output at 8 µm, including power and wavelength tuning.

Main Results:

• Successful demonstration of first-order quasi-phase-matched DFG in orientation-patterned GaAs.
• Generation of tunable mid-IR light at 8 µm with output power consistent with theoretical predictions.
• Excellent material uniformity observed over a 19-mm-long and 500-µm-thick device, confirmed by consistent performance.

Conclusions:

• Orientation-patterned GaAs is a highly effective material for generating narrowband tunable mid-IR light via DFG.
• The all-epitaxial fabrication method yields high-quality crystals suitable for nonlinear optical applications.
• The demonstrated performance indicates significant potential for this technology in spectroscopy, sensing, and other mid-IR applications.