Cylinder: Qsca vs Wavelength

This example demonstrates how to compute and visualize the scattering efficiency (Qsca) as a function of wavelength for cylindrical scatterers using PyMieSim, considering cylinders with different diameters and refractive indices.

Importing the package dependencies: numpy, PyMieSim

import numpy as np
from PyMieSim.experiment.scatterer import Cylinder
from PyMieSim.experiment.source import Gaussian
from PyMieSim.experiment import Setup
from PyMieSim import measure

Defining the source Studying the scattering efficiency across a range of wavelengths.

source = Gaussian(
    wavelength=np.linspace(400e-9, 1000e-9, 500),  # Wavelengths ranging from 400 nm to 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 Considering cylinders with specific diameters and refractive indices.

scatterer = Cylinder(
    diameter=[200e-9, 150e-9, 100e-9],  # Array of diameters: 200 nm, 150 nm, 100 nm
    index=[2, 3, 4],  # Array of refractive indices: 2, 3, 4
    medium_index=1,  # Refractive index of the surrounding medium
    source=source
)

Setting up the experiment

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

Measuring the scattering efficiency (Qsca) Averaging the data across the different indices to simplify visualization.

data = experiment.get(measure.Qsca)
data = data.mean(experiment.index)

Plotting the results Visualizing how the Qsca varies with wavelength for the given cylinder configurations.

figure = data.plot(
    x=experiment.wavelength,  # Wavelength as the x-axis
    y_scale='linear'  # Linear scale for the y-axis
)

Displaying the plot

_ = figure.show()