clc;?clear?all;?close?all;?clf;
cputime=0;
tic;
ln=1;
i=sqrt（-1）;
Po=.001;?%?input?pwr?in?watts
alpha=0.2;?%?Fiber?loss?value?in?dB/km
alph=alpha/（4.343）*1e-3;?%Ref?page#55?eqn?2.5.3?Fiber?optic?Comm?by?GP?Agrawal???%unit?1/m
gamma=0.003;?%fiber?non?linearity?in?/W/m
to=125e-12;?%initial?pulse?width?in?second
C=-2;?%Input?chirp?parameter?for?first?calculation
b2=-20e-27;?%2nd?order?disp.?（s2/m）?????????????????????????????
Ld=（to^2）/（abs（b2））;?%dispersion?length?in?meter????????????????????????????%
pi=3.1415926535;
Ao=sqrt（Po）;?%Amplitude
%----------------------------------------------------------
tau?=-?4096e-12:1e-12:?4095e-12;%??dt=t/to
?dt=1e-12;
?rel_error=1e-5;
?h=100;%?step?size
?
?%%%%%%%%%%
???u=Ao*exp（-（（1+i*（-C））/2）*（tau/to）.^2）;%page#47?G.P.AGrawal???????????????%原始脈沖波形，參考光纖通信系統PPT-chapter2-Optical?Fiber-2?Page3
???figure（1）
???plot（abs（u）‘r‘）;
???title（‘Input?Pulse‘）;?xlabel（‘Time‘）;?ylabel（‘Amplitude‘）;
grid?on;
hold?on;
l=max（size（u））;??
%%