A near-infrared laser diode excitation source for effectively increasing the near-infrared performance of an SLM/Aminco 8000C fluorometer is described. This laser diode excitation source provides high power monochromatic excitation for extremely low detection limits. Evaluation of the laser diode excitation source and stability is monitored by a series of calibration curves. The paper presents the advantages of laser diode excitation sources in spectroscopic applications. The laser diode described can also be used for simultaneous absorbance measurements if laser diode intracavity effect is utilized. The design and implementation of a simple controlling circuit for accurately maintaining the laser power of the laser diode are also described.