In a laser tracking system (LTS) the objective is to track the reflected or scattered modulated laser beam. A four-quadrant is essentially required to center and align the optical axis of the quad detector (QD) with the main laser beam. This paper shows an experimental characterization of a high power diode laser module as a laser target designator source (LTD) used in the tracking system. It includes the (I-V) characteristic, output optical power verses driving electrical currents, slope efficiency, the laser beam profile and the wavelength dependence of temperature. Like all practical designation and tracking system, a modulation of a high power laser source with pulse repetition frequencies (PRF) mode of operation is required. So the effect of different frequencies on both of the pulse to pulse stability and wavelength stability are measured, analyzed and investigated.