[en] The anticipated physics program for the International Linear Collider (ILC) requires a highly granular hadronic calorimeter. One option for such a tracking calorimeter is a scintillator-steel sandwich structure placed inside the magnetic coil. The development of hadronic showers will be studied with a physics prototype, in order to improve current models. This prototype, currently being built within the collaboration for a CAlorimeter for the LInear Collider Experiment (CALICE) at the Deutsches Elektronen-Synchrotron (DESY) also serves to test a new semiconductor based photodetector the so called silicon photomultiplier. The calibration of these new photodetectors requires to take into account their nonlinear response.The response function, describing this behaviour, is investigated in this thesis. A calibration and monitoring system, needed to correct for the temperature and voltage dependence of the silicon photomultiplier signals and to observe changes of their response over time, is optimised and tested. (orig.)