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start implementation of class based simulation of a IM/DD communication system. Mostly based on Move-It but cleaned up and with focus on direct detection, however I try to keep the versatility of move-it alive.
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Silas Oettinghaus
2023-05-12 15:28:23 +02:00
parent 69df41340f
commit 6d53823466
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Classes/EML.m Normal file
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classdef EML
%EML External Modulated Laser
% Detailed explanation goes here
properties
%class input objms
mode
fsimu %in Hz
lambda %in nm
power %in dBm
linewidth %in Hz
ampl_imbal
pha_imbal
bias
u_pi
%on instance creation
field
noisefactor
phase %eigentlich nur wichtig wenn man mehrere blöcke durchsimuliert...
real_factor
imag_factor
%during simulation
signal_len
end
methods
function obj = EML(options)
%EML Construct an instance of this class
% Detailed explanation goes here
arguments
options.mode;
options.fsimu;
options.lambda;
options.power;
options.linewidth = 0;
options.ampl_imbal = 0;
options.pha_imbal = 0;
options.bias;
options.u_pi;
end
obj.mode = options.mode;
obj.fsimu = options.fsimu;
obj.lambda = options.lambda;
obj.power = options.power;
obj.linewidth = options.linewidth;
obj.ampl_imbal = options.ampl_imbal;
obj.pha_imbal = options.pha_imbal;
obj.bias = options.bias;
obj.u_pi = options.u_pi;
obj.field=sqrt(10^(obj.power/10-3)); %dbm to sqrt(mw)
obj.noisefactor=sqrt(2*pi*obj.linewidth/obj.fsimu);
obj.phase=0;
if obj.mode==4 || obj.mode==5
obj.real_factor=(1+obj.ampl_imbal/2)*exp(1i*obj.pha_imbal/2);
obj.imag_factor=(1-obj.ampl_imbal/2)*exp(1i*(pi/2-obj.pha_imbal/2));
end
end
function [opt_out,obj] = process(obj,elec_in)
%METHOD1 Summary of this method goes here
% Detailed explanation goes here
%needed later
obj.signal_len = length(elec_in);
% generate phase noise of laser
% scale with signal energy in sqrt(mw)
if obj.linewidth ~= 0
ph_noi = obj.createPhaseNoise;
laserfield = obj.field.*exp(1i*ph_noi);
else
laserfield = obj.field;
end
%modulate the laserfield with the electrical signal
opt_out = obj.externalmodulation(laserfield,elec_in);
%remember phase (! you need to receive the altered eml object in you sim program !)
obj.phase = ph_noi(end);
end
function noi = createPhaseNoise(obj)
%create random vector
noi = randn(obj.signal_len,1);
%scale with noisefactor
noi = noi * obj.noisefactor;
%cumsum to accumulate noise over time vector
noi = cumsum(noi);
%add phase from previous block/ loop of simulation
noi = noi + obj.phase;
end
function modulated_laserfield = externalmodulation(obj,laserfield,electrical_in)
switch obj.mode
case 1 % linear IM
modulated_laserfield = laserfield.*sqrt(real(electrical_in + obj.bias)/obj.u_pi);
case 2 % IM with hMZM function
modulated_laserfield = laserfield.*cos(pi/2*(real(electrical_in)+obj.bias)/obj.u_pi);
case 3 % PMsi
modulated_laserfield = laserfield.*exp(1i*pi*real(electrical_in)/obj.u_pi);
case 4 % linear IQ-Modulator
if obj.ampl_imbal ==0 && obj.pha_imbal == 0
% No IQ Imbalance
modulated_laserfield=laserfield.*electrical_in/obj.u_pi;
else
% with IQ Imbalance
modulated_laserfield = laserfield.*(real(electrical_in)*obj.real_factor/obj.u_pi...
+imag(electrical_in)*obj.imag_factor/obj.u_pi);
end
case 5 % IQ-Modulator with cosine function
modulated_laserfield = laserfield/sqrt(2).*(cos(pi/2*(real(electrical_in)+obj.bias)/obj.u_pi)*obj.real_factor...
+cos(pi/2*(imag(electrical_in)+obj.bias)/obj.u_pi)*obj.imag_factor);
end
end
end
end