diff --git a/Classes/02_optical/Optical_Demultiplex.m b/Classes/02_optical/Optical_Demultiplex.m
index fc2bc36..7d7c39e 100644
--- a/Classes/02_optical/Optical_Demultiplex.m
+++ b/Classes/02_optical/Optical_Demultiplex.m
@@ -113,8 +113,35 @@ classdef Optical_Demultiplex < handle
             pha = mod(-2*pi*(0:blocklen_in-1).'.*df_T/obj.fs_in, 2*pi);
             lo  =  cos(pha)+1i*sin(pha);
 
-            x_envelopes = ifft(fft(att.*signal_in(:,1).*lo).*H);
-            y_envelopes = ifft(fft(att.*signal_in(:,2).*lo).*H);
+            % x_envelopes = ifft(fft(att.*signal_in(:,1).*lo).*H);
+            % y_envelopes = ifft(fft(att.*signal_in(:,2).*lo).*H);
+
+            N = size(lo,1);
+            C = size(lo,2);
+
+            x_envelopes = zeros(N, C, 'like', signal_in);
+            y_envelopes = zeros(N, C, 'like', signal_in);
+
+            s1 = signal_in(:,1);
+            s2 = signal_in(:,2);
+
+            % Reusable work buffers (avoid reallocations)
+            wrk_time = zeros(N,1, 'like', signal_in);
+            wrk_freq = zeros(N,1, 'like', signal_in);
+
+            for c = 1:C
+                % ---- X branch ----
+                wrk_time(:) = att .* s1 .* lo(:,c);   % N×1
+                wrk_freq(:) = fft(wrk_time);          % N×1
+                wrk_freq(:) = wrk_freq .* H;          % N×1
+                x_envelopes(:,c) = ifft(wrk_freq);     % N×1
+
+                % ---- Y branch ----
+                wrk_time(:) = att .* s2 .* lo(:,c);
+                wrk_freq(:) = fft(wrk_time);
+                wrk_freq(:) = wrk_freq .* H;
+                y_envelopes(:,c) = ifft(wrk_freq);
+            end
  
         end
     end
diff --git a/projects/WDM/WDM_model.m b/projects/WDM/WDM_model.m
index 10e6c69..9563ef6 100644
--- a/projects/WDM/WDM_model.m
+++ b/projects/WDM/WDM_model.m
@@ -3,7 +3,7 @@
 % --- FIRST LINE: evaluate settings located beside this script ---
 run(fullfile(fileparts(mfilename('fullpath')),'WDM_settings.m'));
 
-num_realiz      = 1;
+num_realiz      = 50;
 % wavelengthplan  = calcWavelengthPlan(16,400e9,1310);
 wavelengthplan  = [1295,1305,1315,1325];
 link_length     = 2;
@@ -65,7 +65,7 @@ signal_cell = {};
 Symbols = {};
 Tx_bits = {};
 
-rop = linspace(-11,0,8);
+rop = -8.25:0.75:0;
 
 output_ffe = cell(length(wavelengthplan),length(rop),num_realiz);
 output_vnle = cell(length(wavelengthplan),length(rop),num_realiz);
@@ -75,7 +75,7 @@ output_dbt = cell(length(wavelengthplan),length(rop),num_realiz);
 for realiz = 1:num_realiz
 
   
-    for l = 1:N
+    parfor l = 1:N
     
         [Digi_sig,Symbols{l},Tx_bits{l}] = PAMsource(...
             "fsym",fsym,"M",M,"order",18,"useprbs",0,...
@@ -103,7 +103,7 @@ for realiz = 1:num_realiz
         signal_cell{l} = Polarization_Controller("mode","rot_power","desired_power",30).process(Eml_out);
     end
     
-    Opt_sig_wdm = Optical_Multiplex("fs_in",signal_cell{l}.fs,"fs_out",upsample_pow*Eml_out.fs,...
+    Opt_sig_wdm = Optical_Multiplex("fs_in",fdac*kover,"fs_out",upsample_pow*fdac*kover,...
                                 "lambda_center",1310,"random_key",0,"filtype",1,"B",200e9).process(signal_cell);
     
     Opt_sig_wdm = Amplifier("amp_mode","ideal_no_noise","gain_mode","output_power","amplification_db",3+10*log10(N)).process(Opt_sig_wdm);
@@ -250,8 +250,8 @@ cols = linspecer(N);
 for l = 1:N
     % plot(rop,mean(squeeze(ber_vnle(l,:,:)),2,'omitnan'),'Marker','*','DisplayName',sprintf('Ch: %d',wavelengthplan(l)))
     % plot(rop,cellfun(@(c) c.metrics.BER, output_ffe(l,:), 'UniformOutput', true),'Marker','*','DisplayName',sprintf('Ch: %d',wavelengthplan(l)),'Color',cols(l,:),'HandleVisibility','on','LineStyle',':');
-    plot(rop,cellfun(@(c) c.metrics.BER, output_vnle(l,:), 'UniformOutput', true),'Marker','x','DisplayName',sprintf('Ch: %d',wavelengthplan(l)),'Color',cols(l,:),'HandleVisibility','on','LineStyle','--')
-    plot(rop,cellfun(@(c) c.metrics.BER, output_mlse(l,:), 'UniformOutput', true),'Marker','o','DisplayName',sprintf('Ch: %d',wavelengthplan(l)),'Color',cols(l,:),'HandleVisibility','on','LineStyle','-')
+    plot(rop,cellfun(@(c) c.metrics.BER, res.vnle(l,:), 'UniformOutput', true),'Marker','x','DisplayName',sprintf('Ch: %d',wavelengthplan(l)),'Color',cols(l,:),'HandleVisibility','on','LineStyle','--')
+    plot(rop,cellfun(@(c) c.metrics.BER, res.mlse(l,:), 'UniformOutput', true),'Marker','o','DisplayName',sprintf('Ch: %d',wavelengthplan(l)),'Color',cols(l,:),'HandleVisibility','on','LineStyle','-')
 end
 yline([3.8e-3,2.2e-4],'HandleVisibility','off');
 ylabel('BER');