Modeling Coherent Nonlinear Microscopy of Axially Layered Anisotropic Materials Using FDTD

TL;DR

This paper extends a finite-difference time-domain (FDTD) modeling approach to simulate coherent nonlinear microscopy of layered anisotropic materials, addressing phase-matching complexities in heterogenous samples.

Contribution

The authors develop and validate an FDTD-based simulation method for anisotropic layered materials in nonlinear microscopy, expanding previous diagonal susceptibility models.

Findings

Validated FDTD simulations on layered anisotropic geometries

Enhanced understanding of phase-matching in heterogenous samples

Improved modeling accuracy for nonlinear microscopy images

Abstract

Providing quantitative interpretation of coherent nonlinear microscopy images, such as third-harmonic generation (THG), is generally hampered by the complex phase-matching conditions, especially in the presence of sample linear heterogeneity. We recently presented a numerical pipeline using the finite-difference time-domain (FDTD) method to take this heterogeneity into account. However, due to software restrictions, we only considered nonlinear materials with diagonal nonlinear susceptibilities. We now expand the recently developed FDTD approach to model nonlinear microscopy for anisotropic materials that obey Kleinman Symmetry, organized in layers along the optical axis, and validate our simulations on well-described geometries.