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# how to solve my problem that i write

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I write this code and i wanne output that show me like a sinc function like picture that i attached. the other point is about my l value that i defined it, i wanne some random number between 11e-6 till 13e-6, is it true like this that i define?

tnx.

clc;

clear;

close all;

capital_lambda = 20e-6;

% define sellmier equation to obtain refractive index

lambda_sh=0.775e-6; % SH wavelength

nlithium_sh = 2.1784;

lambda_ff=1.55e-6; % FF wavelength

nlithium_ff = 2.1376;

% parameters

capital_lambda = 20e-6;

k_sh=(2*pi/lambda_sh)*nlithium_sh;

k_ff=(2*pi/lambda_ff)*nlithium_ff;

Delta_kk = k_sh-2*k_ff;

%km=2*pi/capital_lambda;

L = 1; % Length;

sigma_l = 2; % sigma_l = l*sigma_avg

N=L/(capital_lambda/2); % number of domains

l=unifrnd(11e-6,13e-6,[1,1000]); %

for i=l

f=exp(-(pi.^2) .* (sigma_l.^2)/2.*(l.^2));

Delta_k=(k_sh-2*k_ff)-pi./l;

E3= f .* (sinc((Delta_k .* L)/2)).^2 + ((1-f)/N);

end

plot(E3)

%plot(abs(fftshift(fft2(E3))))

xlabel('(Delta_k * L)/pi');

ylabel('SHG Effiency');

##### 0 Comments

### Answers (1)

Hassaan
on 22 Apr 2024

Edited: Hassaan
on 22 Apr 2024

clc;

clear;

close all;

% Constants and parameters

lambda_sh = 0.775e-6; % SH wavelength

nlithium_sh = 2.1784;

lambda_ff = 1.55e-6; % FF wavelength

nlithium_ff = 2.1376;

L = 1; % Length in some units, assuming meters

% Wave numbers

k_sh = (2 * pi / lambda_sh) * nlithium_sh;

k_ff = (2 * pi / lambda_ff) * nlithium_ff;

% Define the range of Delta_k*L/pi to evaluate the sinc-squared function

delta_kL_over_pi = linspace(-20, 120, 10000); % For a smooth curve

Delta_k = delta_kL_over_pi * pi / L;

% Calculate the sinc-squared function

E3 = sinc(Delta_k / (2*pi)).^2;

% Plotting

figure;

semilogy(delta_kL_over_pi, E3, 'LineWidth', 2);

xlabel('\Delta k L/\pi');

ylabel('Relative Efficiency |g|^2');

title('Second Harmonic Generation Efficiency');

grid on; % Adding grid for better readability

axis tight; % Remove extra white space in the plot

-----------------------------------------------------------------------------------------------------------------------------------------------------

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