Mode Suppression Ratio of CW Laser Diode and its Influence on Optical Communication Network

Abstract:<br /> The influence of mode suppression ratio on the dynamics of semiconductor laser will be investigated in this paper, especially in a high bit rate optical communication. An optical communication network of fiber length of 50 km was established, with semiconductor laser modulated at 10(Gbps). Mode suppression ratio of more than 20 dB was an optimum value for a laser diode to be considered as a single mode laser. We have taken into account in this study the following factors namely; the number of longitudinal modes, the relative intensity noise, laser mode linewidth, and chirping. The result showed that, the quality factor and bit error rates were affected by the mode suppression ratio. Relative intensity noise of (-100 dB/Hz) had an extreme drop in the received power and more fluctuations were found in the power output spectra. Intramodal distortion was observed in the optical layout system when chirping was considered in the laser characteristic.