5.2-5.6-microm source tunable by frequency conversion in a GaAs-based waveguide.

Area of Science:

• Optoelectronics
• Nonlinear Optics
• Materials Science

Background:

• Semiconductor heterostructures are crucial for advanced optical devices.
• Difference-frequency generation (DFG) is a key technique for generating tunable infrared light.
• Efficient mid-IR sources are needed for various applications like molecular spectroscopy.

Purpose of the Study:

• To demonstrate a tunable mid-infrared (mid-IR) source.
• To utilize a selectively oxidized GaAsAlAs multilayer waveguide for nonlinear frequency conversion.
• To achieve phase matching and minimize losses for mid-IR radiation.

Main Methods:

• Fabrication of a selectively oxidized GaAsAlAs multilayer waveguide.
• Implementation of difference-frequency generation (DFG) using two pump wavelengths.
• Tuning the mid-IR output by adjusting waveguide temperature and pump wavelength.
• Measurement of output power and optical losses.

Main Results:

• Achieved tunable mid-IR generation from 5.2 to 5.6 µm.
• Obtained a maximum mid-IR output power of 0.12 µW for a pump power product of 7 mW².
• Measured optical losses of approximately 50 cm⁻¹ for the mid-IR radiation.
• Attributed observed losses to surface scattering effects.

Conclusions:

• A tunable mid-IR source was successfully demonstrated using a GaAsAlAs multilayer waveguide.
• The waveguide design enables phase matching for nonlinear optical interactions.
• Further optimization is needed to reduce scattering losses and enhance output power.