# Want MATLAB code

1. Jul 19, 2010

### almesba

Can any one help me by giving MATLAB code to simulate semiconductor laser rate equation by finite difference methord. i wrote a code but that was not working. so i need it badly. please help me.

Last edited by a moderator: Jul 19, 2010
2. Jul 19, 2010

### Staff: Mentor

No, sorry. We do not do your schoolwork for you. Perhaps if you post your code (like you did in your other thread), we may be able to spot any errors....

3. Jul 19, 2010

### almesba

mmm=0;
for nW=[1 3 5]
mmm=mmm+1;
mm=0;
Lam=980e-9;
q=1.6e-19;
alpha=.2;
Tn=1;
Tp=2.8e1;
G0=0.6;
N0 = 1e24;
h=6.6e-34;
c=3e8;
Gamma=1e-5;
beta=1;
epsilon=1e-12;
Va=3.75e-14;
Ith=((q*Va)/Tn)*(N0+(1/(Gamma*G0*Tp)));
for I = 0.1e-3:0.1e-3:4.5e-3;
mm=mm+1;
tini=0;
tfin=4e-9;
dt=1e-12;
m=0;
N(1)=0;
S(1)=0;
for t=tini:dt:tfin
m=m+1;
delN=I/(q*Va)-N(m)/Tn-G0*(N(m)-N0)*S(m)/(1+epsilon*S(m));
delS=S(m)+Gamma*beta*N(m)/Tn+Gamma*(N(m)-N0)*S(m)/(1+epsilon*S(m));

N(m+1)=N(m)+dt*delN;
S(m+1)=S(m)+dt*delS;
P(m+1)=1000*Va*S(m)*h*c/(Lam*2*Gamma*Tp);
tt(m+1)=t;

end
II(mm)=I*1e3;
Po(mmm,mm)=sum(N(1:4000))/4000;
N1(mmm,mm)=sum(N(1:4000)/4000);

Po1(mmm,:)=P;
Nt(mmm,:)=N;
S1(mmm,:)=S;
end
end

tt=tt*1e-9;
figure(1)
plot(tt,N);
figure(2)
plot(tt,S);

4. Jul 20, 2010

### Staff: Mentor

What is "not working"? You really need to be more clear in your posts here on the PF.

5. Jul 20, 2010

### almesba

Thank you. I solved the problem.