170 lines
4.0 KiB
Matlab
170 lines
4.0 KiB
Matlab
classdef Fiber
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%FIBER Summary of this class goes here
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% Detailed explanation goes here
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properties
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fsimu
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fiber_length
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alpha
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D
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Dslope
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lambda0
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gamma
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dphimax
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b2
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b3
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alpha_lin
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linstep
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end
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methods
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function obj = Fiber(options)
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%FIBER Construct an instance of this class
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% Detailed explanation goes here
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arguments
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options.fsimu
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options.fiber_length = 0
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options.alpha = 0.2
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options.D = 17
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options.Dslope = 0.06
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options.lambda0 = 1550
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options.gamma = 0.0013
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options.dphimax = 5e-3
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end
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obj.fsimu = options.fsimu;
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obj.fiber_length = options.fiber_length*1000; %km
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obj.alpha = options.alpha;
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obj.D = options.D*1e-6;
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obj.Dslope = options.Dslope*1e3;
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obj.lambda0 = options.lambda0*1e-9;
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obj.gamma = options.gamma;
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obj.dphimax = options.dphimax;
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obj.b2 = -obj.D*obj.lambda0^2/(2*pi*Constant.LightSpeed);
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obj.b3 = ((obj.lambda0.^2/(2*pi*Constant.LightSpeed)).^2*obj.Dslope);
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obj.alpha_lin = obj.alpha/10*log(10)/1000;
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end
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function signalclass_out = process(obj,signalclass_in)
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% actual processing of the signal (steps 1. - 3.)
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signalclass_in.signal = obj.process_(signalclass_in.signal);
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% append to logbook
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lbdesc = 'Fiber ';
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signalclass_in = signalclass_in.logbookentry(lbdesc);
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% write to output
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signalclass_out = signalclass_in;
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end
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function opt_out = process_(obj,opt_in)
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%METHOD1 Summary of this method goes here
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% Detailed explanation goes here
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N = length(opt_in);
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faxis = linspace(-obj.fsimu/2,obj.fsimu/2,N+1);
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faxis = ifftshift(faxis(:,1:end-1));
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faxis = faxis';
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obj.linstep = -obj.alpha_lin/2 - 2*1j*pi^2*obj.b2*faxis.^2 - 4/3*1j*pi^3*obj.b3*faxis.^3;
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if obj.gamma ~= 0
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opt_out = obj.NLSE(opt_in);
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else
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opt_out = ifft(fft(opt_in).*exp(obj.linstep*obj.fiber_length)); % only one linear step
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end
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%attenuate nase
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end
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function [yout] = NLSE(obj, xin)
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maxPow = obj.gamma.*max(abs(xin).^2);
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Leff = obj.dphimax / maxPow ;
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dz = Leff;
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z_prop = 0;
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yout = fft(xin);
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yout = ((yout).*exp(obj.linstep*dz/2));
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while true
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yout = ifft(yout);
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Leff = dz;
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power = abs(yout).^2;
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Hnl = exp( -1j*obj.gamma*power*Leff);
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yout = yout .* Hnl;
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z_prop = z_prop + dz;
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maxPow = obj.gamma*max(abs(yout).^2);
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Leff = obj.dphimax/maxPow;
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dz_new = Leff;
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if z_prop + dz_new > obj.fiber_length
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dz_new = obj.fiber_length - z_prop;
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break
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end
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yout = fft(yout);
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yout = ((yout).*exp(obj.linstep*(dz/2+dz_new/2)));
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dz = dz_new;
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end
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yout = fft(yout);
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yout = ((yout).*exp(obj.linstep*(dz/2+dz_new/2)));
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yout = ifft(yout);
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Leff = dz;
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power = abs(yout).^2;
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Hnl = exp( -1j*obj.gamma*power*Leff);
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yout = yout .* Hnl;
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yout = fft(yout);
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yout = ((yout).*exp(obj.linstep*(dz/2)));
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yout = ifft(yout);
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end
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end
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end
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