The design of Fiber Optic Communication (FOC) systems requires many optical and electronic operational parameters for specifying and optimizing the selection of components in a communication link. An analysis method is developed using the noise effective temperature concept. This approach allows a unified NoiseBandwidth parametric analysis of analog, digital or combined modulation formats in FOC systems. A typical real life system analysis is presented, demonstrating the system bandwidth dependence on various noise sources contributions, originating from the electrical and optical parts. To this end, simple models for both optical and electronic components are used.