Analog Fiber Optics: Pragmatic Considerations Beyond the Textbook

This report discusses the use of AlGaAs lasers and LEDs as optical sources for a multimode fiber optic link that uses analog modulation. It is well known that the limited linearity of these sources makes digital modulation a preferable method to send information. However, many factors determine how a portion of an information transfer system is constructed or retrofitted including previous investments in associated electrical and electro optical hardware, the cost of redesigning the system architecture, and, in some instances, the difficulty in digitizing certain modulation waveforms. This report is written primarily for the fiber optic design engineer that uses analog modulation, for whatever justification, but many aspects will also be of use for those who design with the traditional digital approach.