Determination of nonlinear refractive index in a Ta2O5 rib waveguide using self-phase modulation

Area of Science:

• Nonlinear optics
• Materials science
• Waveguide optics

Background:

• Self-phase modulation (SPM) is a key nonlinear optical phenomenon.
• Tantalum pentoxide (Ta2O5) waveguides are potential candidates for integrated photonic devices.
• Understanding the nonlinear properties of waveguide materials is crucial for device design.

Purpose of the Study:

• To investigate self-phase modulation in Ta2O5 rib waveguides.
• To determine the nonlinear refractive index (n2) of Ta2O5.
• To assess the influence of group velocity dispersion (GVD) on nonlinear measurements.

Main Methods:

• Propagation of 800nm ultrashort pulses through a 1 cm-long Ta2O5 rib waveguide.
• Estimation of the nonlinear refractive index (n2) using simplified theory.
• Femtosecond time-of-flight measurements with a Kerr shutter configuration to evaluate GVD.

Main Results:

• Self-phase modulation was successfully observed in the Ta2O5 waveguide.
• The nonlinear refractive index (n2) was measured to be 7.23x10^-19 m^2/W.
• Group velocity dispersion at 800nm was found to be negligible, validating the simplified n2 estimation.

Conclusions:

• Ta2O5 exhibits a nonlinear refractive index over an order of magnitude higher than silica glass.
• The low dispersion at 800nm simplifies the analysis of nonlinear optical effects in Ta2O5 waveguides.
• Ta2O5 is a promising material for nonlinear photonic applications requiring high nonlinearity and low dispersion.