The paper presents the model of a complete multidomain system involving two opto-electronic components: the emitter and the receiver. It is written in Anacad Mentor Graphics HDL-A and integrates the propagation environment characteristics and the thermal behavior of each components. First, packages describing electrical, optical, and thermal behavior of each component. First, packages describing electrical, optical, and thermal domains are detailed. Second, the models of the components are explained. They include an electrical, a thermal and an optical part, the latter being particularly developed. Third, the models of the propagation environment, an optical fiber and the related free space, are presented. The components are assembled to build a compete instrumented opto-electronic transmission system. The laser diode emits a digital clock through an optical fiber to a photodiode. The laser diode is thermal controlled through a Peletier module, which can be deactivated as needed. The alignment of the laser diode with the optical fiber can be studied/modified too. The HDL-A resulting models have been simulated in the ELDO environment. Results show that thermal variations influence the quality of the transmission.