arXiv subjects

Cael Warner

Publications and source records attributed to Cael Warner.

4 recordsLinked to original sources

arXiv2025

Comparing time and frequency domain numerical methods with Born-Rytov approximations for far-field electromagnetic scattering from single biological cells

The Born-Rytov approximation estimates effective refractive index of biological cells from measurements of scattered light intensity, polarization and phase. Effective refractive index is useful for estimating a biological cell's dry mass, volume, and internal morphology directly from its elastic light scattering pattern. This work compares the Born-Rytov approximation with analytical, Yee-lattice finite-difference time-domain, and discrete-dipole approximations to Maxwell's equations in the cases of electromagnetic scattering from a sphere and a tomographic reconstruction of Saccharomyces cerevisiae. Practical advantages and limitations of each numerical method are compared for modeling electromagnetic scattering of both near-field intensity and the far-field projected intensity, in terms of accuracy, memory, and compute time. When compared with a commercial software implementation of the Yee-lattice finite-difference time domain method, the Born-Rytov scattering approximation and discrete dipole approximation show better agreement with the far-field light scattering pattern from Saccharomyces cerevisiae.

physics.comp-ph↗

arXiv2025

Low-dispersion low free-spectral-range Mach-Zehnder interferometer with long straight path lengths on silicon

Multiple Mach-Zehnder interferometers are constructed using fiber-Bragg grating couplers, y-branches, silicon waveguides, and/or broadband splitters in silicon on insulator strip waveguides to test the effect of variation in waveguide length between consecutive bends on the transmission gain spectrum, free-spectral range, group refractive index, and dispersion. Dispersion is mitigated by increasing the path length between consecutive bends of minimum radius. With long linear waveguide sections, a free spectral range of 0.41 nm is achieved.

physics.optics↗

arXiv2025

Simulation of silicon ridge waveguide enhanced two-photon absorption from femtosecond pulses

Field enhancement of two-photon absorption from a 50-fs pulse on a silicon ridge waveguide is simulated for a varying energy downward propagating 800+/-9.42 nm wavelength plane-wave orthonormal to a waveguide in 2D FDTD using ANSYS Lumerical FDTD. Energy absorbed by the waveguide is enhanced due to mode confinement within the standard 500 nm width, 130 nm height silicon ridge waveguide on 90 nm thick silicon and 3 {\mu}m silicon dioxide insulator.

physics.optics↗

arXiv2022

Modeling dispersive silver in the electrodynamic lattice-Boltzmann method using complex-conjugate pole-residue pairs

The polarization density of a broadband electrodynamic lattice-Boltzmann method (ELBM) is generalized to represent frequency-dispersion of materials interacting with electromagnetic waves. The frequency-dependent refractive index and extinction coefficient are modeled using complex-conjugate pole-residue pairs in an auxiliary-differential-equation (ADE). Electric and magnetic fields are evaluated on a single lattice, ensuring a stable numerical solution up to the Nyquist limit. The electric and magnetic fields from the ELBM are compared with the electric and magnetic fields from the finite-difference-time-domain (FDTD) method. Accurate transmittance of a 100 nm silver slab is extracted from the transmitted power spectrum of a broadband Dirac-delta wave-function for photon energies ranging from 0.125-5 eV. Given this capability, the ELBM with an ADE is an accurate and computationally efficient method for modeling broadband frequency-dispersion of materials.

eess.SY↗