A detailed thermoptical analysis of dye-doped Polymer Dispersed Liquid Crystal (D-PDLC) systems has been performed. A comparison of the optical properties between DPDLCs and not doped PDLCs based on the same polymeric matrix is addressed. For any D-PDLC composition investigated, the light intensity and the sample temperature are used to control or adjust the nonlinear part of its refractive index. We investigated the thermal responses of PDLC samples prepared with three different dyes at two dopant concentrations in order to evaluate the contribute of the dopants as a function also of its percentage in the polymeric matrix. Our experimental results demonstrate that self transparency effect, optical hysteresis and thermo-optical modulation are notably affected by the used dye. We show how the use of dye in preparing PDLC can be useful in order to design thermo-optical devices employing waveguides connected with the considered materials or to realise low cost thermal sensors.