Recently, major advances have been reached in the fluorescence detection of small amounts of molecules in liquids, making possible even the detection of single molecules in liquid flows. Significant improvements of fluorescence detection techniques make single molecule detection feasible for many applications, especially in the field of molecular biology and genetics. For such techniques new compact and inexpensive lasers are desirable. laser diode systems are the most favorable candidates for such light sources. With the expanding number of available NIR-fluorescent dyes, the importance of cheap and reliable laser light sources above 630 nm will increase. But not only cw-laser systems are of growing interest. In a number of recent papers, the application of time-resolved fluorescence detection down to a single molecule level was shown to be of great use for further improving detection efficiency. Thus, one needs high- repetition rate pulsed laser diode systems with good time and optical performance, and detection electronics with high-speed and large data throughput. Here we present such a system, combining a pulsed diode laser system with excellent electrical and optical parameters, and a high speed electronic for time correlated single photon counting. This system is suitable for a broad range of applications in ultra sensitive fluorescence detection.