General framework for ultrafast nonlinear photonics: unifying single and multi-envelope treatments [Invited].

Area of Science:

• Nonlinear Optics
• Computational Photonics
• Waveguide Optics

Background:

• Numerical modeling of ultrashort pulse propagation is crucial for understanding nonlinear optical devices.
• Existing models (single- vs. multi-envelope) create a mismatch for octave-spanning spectra, especially in chi(2) devices.
• Spectral overlap and nonlinear polarization terms complicate modeling of broadband pulse propagation.

Purpose of the Study:

• To unify single- and multi-envelope modeling approaches for ultrashort pulse propagation.
• To enable direct comparison of different modeling strategies across any optical bandwidth.
• To provide guidelines for selecting appropriate models for device design and numerical efficiency.

Main Methods:

• Development of a common numerical framework for pulse propagation.
• Inclusion of both chi(2) and chi(3) nonlinear interactions.
• Simulation of supercontinuum generation in a LiNbO3 waveguide.

Main Results:

• Demonstrated good agreement between single- and multi-envelope models for octave-spanning spectra.
• Validated the unified framework using experimental data from supercontinuum generation.
• Showcased the utility of the multi-envelope approach for developing reduced models.

Conclusions:

• The unified framework accurately models ultrashort pulse propagation across diverse spectral bandwidths.
• Both single- and multi-envelope models yield comparable results for frequency comb properties.
• The multi-envelope approach offers insights for designing novel ultrafast photonics devices.