Hi I have design Simulation Of DWDM For RZ, NRZ and Coherent QPSK Modulation for free SPACE OPTICAL COMMUNICATION. In my work I analyze that:
1.Coherent QPSK Modulation is Best Among RZ AND NRZ for Free Space Optical Communication.
2. Either Increase in Transmitter Power of Aperture area of the tx and rx will significant improvement in BER.
3. Compare to PIN diode, APD improves BER as Receiver Sensitivity is improved.
4. As we increase our aperture diameters Q factor increases,but for a particular aperture diameter Q factor starts decreasing as we increase the link distance and bit rates.
I am sending you design please find in attachment.