Low-loss pedestal Ta₂O₅ nonlinear optical waveguides

Area of Science:

• Integrated nonlinear optics
• Materials science
• Photonics

Background:

• Tantalum oxide (Ta2O5) is explored for integrated nonlinear optics (NLO).
• Pedestal waveguide design is employed to minimize propagation losses in Ta2O5.
• Achieving low loss and high nonlinearity is crucial for NLO device performance.

Purpose of the Study:

• To investigate a Ta2O5 material platform for integrated NLO applications.
• To characterize the nonlinear refractive index (n2) of Ta2O5 pedestal waveguides.
• To determine propagation losses and assess suitability for various optical spectrum regions.

Main Methods:

• Fabrication of pedestal waveguides with Ta2O5 cores.
• Measurement of spectral broadening from self-phase modulation (SPM) using 23 fs optical pulses at 785 nm.
• Finite Element Method (FEM) analysis for mode characteristics and effective areas.

Main Results:

• A nonlinear refractive index (n2) of (5.8 ± 2.0) × 10^-19 m^2/W was determined for Ta2O5.
• Propagation losses as low as 1.6 dB·cm^-1 (narrow) and 0.1 dB·cm^-1 (large) were achieved.
• High nonlinear and linear refractive indices, wide bandgap, and low losses were confirmed.

Conclusions:

• The Ta2O5 pedestal waveguide platform offers a promising solution for integrated NLO.
• Its properties make it suitable for applications from visible to mid-IR wavelengths.
• Low two-photon absorption is expected in the near-IR due to the wide bandgap.