In this work, the injection-detection in a laser diode is studied as a special case of coherent detection scheme. Signal waveform, amplitude and signal-to-noise ratio are calculated as functions of target distance and total optical attenuation. Several semiconductor laser sources are considered (i.e. Fabry-Perot, DFB and external cavity), and signal dependence on the physical parameters of the sources is analyzed.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.