I am plotting optical Gaussian pulse. I have written the following code but not getting answer

P0_dBm = -5; % in dBm P0_watt = 10^((P0_dBm-30)/10); % in watt FWHM = 0.4*1e-9; %in nanometer sigma = FWHM/(2*sqrt(2*log(2))); mu = 0; Amp = sqrt(P0_watt); x = -10:0.1:10; G_pulse =(1/sqrt(2*pi*(sigma)^2))*exp(-(x-mu).^2./(2*(sigma)^2));%%gaussian pulse pulse= G_pulse/max(G_pulse); plot(x,pulse);