Every day, the need for high speed reliable data transmission increases more and more. One important option is the passive optical networks which use the optical fiber and provides high data rates and long distance. This work investigates the performance of a four users Optical Time Division Multiplexing OTDM over different length of single mode fibers SMF for different bit rates. The effect of utilizing Eribium Dopped Fiber amplifiers EDFAs was investigated for mitigating effect of performance degradations due to attenuation. In order to increase capacity of the system, A hybrid four Wavelength Division Multiplexing WDM and four OTDM system was proposed Dispersion Compensating Fiber DCF was used for reducing the effect of dispersion distortion.