This article describes a study of an 8 W optical output power single emitter laser diode. The used device is the WSLX808008-H-T-PD, manufactured by Wavespectrum, with 808 nm emitted wavelength, and with build in NTC (thermistor), photodiode and Peltier cell. First part of the study explains how the Pspice model of the optical output power is proposed and how parameters are obtained, especially considering temperature variations. A short review of related laser diode theory is done including necessary parameters for the model proposal. It is explained the used method to measure the diode's optical output power avoiding temperature drifts (cold measure) and how the method has been implemented in an automatic characterization system using a data acquisition card controlled with LabVIEW, to be applied at different temperatures using a climatic chamber, and to obtain the necessary model parameters values as required by theory. It is also confirmed that the measured parameters are effectively following the expected theoretical behaviour with the temperature variation. With obtained results, model is proposed and programmed in Pspice, and simulation results are compared with measured real results for model validation. In a second part, it has been studied the usage of laser's wavelength drift as a temperature measurement method, and also as a validation of the cold measurement method as it allows the temperature drift supervision during it. Advantages and disadvantages of this method compared with NTC usage are commented. Results using two different spectrometers, comparison with laser diode manufacturer's information and necessary temperature references for the method are commented. In a third part a proposal of an optical output power measurement setup and it use with diode's characterisation system is proposed. System measurements comparison in DC mode with a thermal power meter and related calibration are performed and applied to the automatic characterization system.