CoreShell: Qback vs Core Diameter

This example demonstrates how to compute and visualize the backscattering efficiency (Qback) as functions of core diameter for CoreShell scatterers using PyMieSim.

Importing the package dependencies: numpy, PyMieSim

import numpy
from PyMieSim.experiment.scatterer import CoreShell
from PyMieSim.experiment.source import Gaussian
from PyMieSim.experiment import Setup
from PyOptik import UsualMaterial
from PyMieSim import measure

Defining the source

source = Gaussian(
    wavelength=[800e-9, 900e-9, 1000e-9],  # Array of wavelengths: 800 nm, 900 nm, 1000 nm
    polarization_value=0,  # Linear polarization angle in radians
    polarization_type='linear',
    optical_power=1e-3,  # 1 milliwatt
    NA=0.2  # Numerical Aperture
)

Defining the scatterer distribution

scatterer = CoreShell(
    core_diameter=numpy.geomspace(100e-9, 600e-9, 400),  # Core diameters from 100 nm to 600 nm
    shell_width=800e-9,  # Shell width of 800 nm
    core_material=UsualMaterial.Silver,  # Core material
    shell_material=UsualMaterial.BK7,  # Shell material
    medium_index=1,  # Surrounding medium's refractive index
    source=source
)

Setting up the experiment

experiment = Setup(
    scatterer=scatterer,
    source=source
)

Measuring the backscattering efficiency (Qback) For demonstrating the measurement of Qsca, a separate call to experiment.get() with measure.Qsca is needed.

data = experiment.get(measure.Qback)

Plotting the results Visualizing how the backscattering efficiency varies with the core diameter.

figure = data.plot(
    x=experiment.core_diameter,  # Core diameter as the x-axis
    y_scale='log'  # Logarithmic scale for the y-axis
)

Displaying the plot

_ = figure.show()