Chao, Xin Qin creator Zhang, Jian-Guo Chairperson Sharma, A.B. Examination Committee Erke, Tapio J. Examination Committee Asian Institute of Technology Partial Scholarship Scholarship donor text series technical report u Bangkok Asian Institute of Technology 1998 continuing eng 76 p. A system configuration is proposed in which the Intensity Modulation (direct modulation) and PIN Direct Detection (IM/DD) scheme is employed in the Wavelength Division Multiplexing system with or without EDF A as optical preamplifier. This approach only need low cost multi-mode Fabry-Perot laser as light source and eliminate the need for an expensive single-mode optical laser. Based on the use of tunable Fabry-Perot optical filter as demultiplexer to select the desired channel signal from multichannel signals, the tradeoff between power efficiency of optical filter and bandwidth efficiency of WDM system has been studied, the optimized optical bandwidth bas been achieved. In this work, the performance of optically preamplified intensity modulation-direct detection (IM-DD) receiver is investigated in terms of bit error rate and sensitivity by employing semiclassical theory coupled with Gaussian approximation method. The analysis provides closed-form expression for sensitivity. Our results show that the total number of uses in WDM system strongly depends on the type of optical filter and the optical bandwidth chosen. In addition our results show direct modulation method limits the capacity of WDM systems due to frequency chirping which relaxes signal spectrum linewidth. We present the very efficient way to improve the capacity of the WDM systems by using forward error correction (FEC) codes. After using FEC the total number of channels which the WDM system can support has been doubled. A thesis submitted in partial fulfillment of the requirement for the degree of Master of Engineering, School of Advanced Technologies Thesis (M.Eng.) - Asian Institute of Technology, 1998 Optical communications Error-correcting codes (Information theory) Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B13569 http://203.159.5.9/ait-thesis/detail.php?q=B13569 050799 20260818134612.0