Widely tunable mid-infrared generation via frequency conversion in semiconductor waveguides.

Area of Science:

• Optics and Photonics
• Semiconductor Devices
• Nonlinear Optics

Background:

• Mid-infrared (mid-IR) light generation is crucial for various applications, including spectroscopy and sensing.
• Semiconductor waveguides offer potential for compact and integrated photonic devices.
• Difference Frequency Generation (DFG) is a nonlinear optical process for generating new frequencies.

Purpose of the Study:

• To demonstrate the generation of mid-IR light at unprecedented wavelengths using DFG in a multilayer AlGaAs waveguide.
• To investigate the tunability of the generated mid-IR light.
• To assess the viability of this platform for monolithic, tunable mid-IR sources.

Main Methods:

• Utilized a multilayer Aluminum Gallium Arsenide (AlGaAs) waveguide.
• Employed difference frequency generation (DFG) by mixing a 1550 nm pump and a 1950 nm signal.
• Phase matching was achieved within the waveguide structure.

Main Results:

• Generated mid-IR light in the 7.5–8.5 μm wavelength range, the longest achieved via DFG in a 2D semiconductor waveguide mode.
• Achieved an efficiency of 1.2×10⁻⁴ %/W in a 1 mm long waveguide.
• Demonstrated tunability over a range greater than 2 μm by adjusting input wavelengths and waveguide geometry.

Conclusions:

• The AlGaAs waveguide platform enables the generation of the longest wavelengths to date for DFG in a 2D semiconductor waveguide mode.
• The demonstrated tunability makes this a promising technology for developing compact, on-chip, tunable mid-IR light sources.
• This work advances the development of integrated photonic solutions for mid-IR applications.