Dichroic mirror embedded in a submicrometer waveguide for enhanced resonant nonlinear optical devices

Area of Science:

• Optics and Photonics
• Materials Science
• Semiconductor Devices

Background:

• Dichroic mirrors are critical optical components for wavelength-selective reflection and transmission.
• Efficient second-harmonic generation (SHG) requires resonant enhancement, necessitating high-quality mirrors.
• Aluminium gallium arsenide (AlGaAs) and aluminum oxide (Al(x)O(y)) offer tunable optical properties for integrated photonics.

Purpose of the Study:

• To design, fabricate, and characterize novel dichroic mirrors integrated into AlGaAs/Al(x)O(y) waveguides.
• To achieve high reflectivity at the fundamental (first-harmonic) wavelength and high transmissivity at the generated (second-harmonic) wavelength.
• To enable resonant enhancement for efficient nonlinear optical processes like SHG.

Main Methods:

• Fabrication of AlGaAs/Al(x)O(y) waveguides with embedded dichroic mirrors.
• Optical characterization of mirror performance, including reflection and transmission spectra.
• Finite-difference time-domain (FDTD) simulations for theoretical analysis and comparison.

Main Results:

• Achieved a maximum reflection of 93% at the first-harmonic wavelength.
• Maintained high transmission at the second-harmonic wavelength.
• Experimental cavity spectra showed excellent agreement with FDTD simulations.

Conclusions:

• The developed dichroic mirrors meet the stringent requirements for SHG resonant enhancement.
• The integrated AlGaAs/Al(x)O(y) waveguide platform is suitable for high-performance photonic devices.
• These mirrors are essential components for advancing integrated nonlinear optics and frequency conversion technologies.