Linewidth

In order to find the linewidth of the laser, the circuit in Fig. 16. was made in INTERCONNECT. Another laser(CWL_1) was added and mixed with the designed ECL, and a RFSA connected to PIN photodetector to record the results. This gives the power to frequency graph shown in Fig. 17. From the graph it can be seen that the spectrum spans across a much larger frequency than expected. This is due to the inability to match the output frequency of the ECL as it varies significantly, so the resulting graph from RFSA would have to span that difference in frequency, one that cannot be fitted to find the linewidth.