how to plot the state of polarisation distribution of a c or v point polarisation singularity using quiver plots

How to plot this state of polarisation distribution using quiver plots for a c point or v point polarisation singularity. Anyone please help.

[Aswathi K]

anyove who knows how to plot these types ellipses using quiver please help

Answer 1

[Milan Bansal]

Hi Aswathi K,

I understand that you want to plot the ellipses as shown in the image using the quiver plot for a c-point or v-point polarization singularity.

The quiver plot in MATLAB plots arrows with specified directional components at the specified Cartesian coordinates. It cannot plot the directional ellipses. However, for a workaround, you can refer to the following steps and the code snippet given below to plot the ellipses for a c-point polarization singularity:

1. Define the grid: Create a grid of points where you want to plot the polarization ellipses.
2. Calculate the ellipse parameters: For each point on the grid, calculate the parameters of the polarization ellipse (orientation, major and minor axes).
3. Plot the ellipses: Use the plot function to draw ellipses at each grid point.

% Define the grid
[x, y] = meshgrid(-10:1:10, -10:1:10);

% Radius of the circular region
R = 10;

% Create a figure
figure;
hold on;
axis equal;
axis off;

% Define the number of points for plotting ellipses
num_points = 50;
t = linspace(0, 2*pi, num_points);

% Loop through each grid point
for i = 1:numel(x)
    % Coordinates
    xi = x(i);
    yi = y(i);
    
    % Only plot ellipses within the circular region
    if sqrt(xi^2 + yi^2) <= R
     
        theta = atan2(yi, xi) / 2; % Orientation of the ellipse
        a = 1 - 0.05 * sqrt(xi^2 + yi^2); % Major axis length 
        b = 0.2 * abs(sin(2*theta)); % Minor axis length
        
        % Parametric equation of the ellipse
        X = a * cos(t);
        Y = b * sin(t);
        
        % Rotate the ellipse by angle theta
        R_matrix = [cos(theta) -sin(theta); sin(theta) cos(theta)];
        ellipse = R_matrix * [X; Y];
        
        % Plot the ellipse at the point (xi, yi)
        plot(xi + ellipse(1, :), yi + ellipse(2, :), 'r', 'LineWidth', 1);
    end
end

% Plot the circular boundary
theta_boundary = linspace(0, 2*pi, num_points);
plot(R * cos(theta_boundary), R * sin(theta_boundary), 'k', 'LineWidth', 2);

Please refer to the following documentation link to learn more about quiver function.

• https://www.mathworks.com/help/matlab/ref/quiver.html

Hope this helps!

[Aswathi K]

Thank you so much, this was the idea I needed

[Aswathi K]

While plotting this we will use ellipticity and azimuth values na??

[Aswathi K]

i have got a edited message, but couldnt see anything??