Compact titanium dioxide waveguides with high nonlinearity at telecommunication wavelengths.

Area of Science:

• Materials Science
• Photonics
• Optical Engineering

Background:

• Photonic integrated circuits (PICs) require advanced waveguide materials for dense integration.
• Existing materials often face trade-offs between compactness, low loss, high nonlinearity, and manufacturability.

Purpose of the Study:

• To fabricate and characterize titanium dioxide (TiO2) waveguides for PICs.
• To evaluate the performance of TiO2 waveguides for nonlinear optical applications.

Main Methods:

• Fabrication of TiO2 waveguides with a 380 nm thick core.
• Measurement of waveguide optical loss and mode size at 1550 nm.
• Characterization of a microring resonator's quality factor.
• Four-wave mixing experiments to determine nonlinear parameters.

Main Results:

• Achieved compact mode size (0.43 μm²) and low loss (5.4 ± 1 dB/cm) at 1550 nm.
• Demonstrated a microring resonator with a loaded quality factor of 53500.
• Measured a high nonlinear parameter (21-34 W⁻¹ m⁻¹) and nonlinear index (2.3-3.6 x 10⁻¹⁸ m²/W).
• Achieved a wavelength conversion efficiency of -36.2 dB.

Conclusions:

• TiO2 waveguides exhibit excellent optical and nonlinear properties suitable for PICs.
• The material's performance, combined with potential for dispersion engineering, makes it promising for nonlinear photonic applications.
• TiO2 offers a viable material solution for mass-produced, high-performance photonic integrated circuits.