Laser-excited remote phosphor systems exhibit advanced characteristics compared to LEDs, such as significantly higher luminance and smaller étendue. Although already in use in some commercial applications, the bottleneck in their performance is considered to be the conversion process within the phosphor layer. The high-intensity exciting laser beam in combination with the low thermal conductivity of ceramic phosphor materials leads to thermal quenching, a phenomenon in which the emission efficiency decreases with rising temperature. A simulation approach that couples the different underlying effects is proposed here. The time-dependent heat equation is solved based on the system’s energy balance equation, while the optical effects are modeled within the geometrical optics regime using a ray tracing algorithm. For simulation purposes the phosphor material can be considered a bulk diffuser, thus the bulk scattering properties are introduced. To conclude, an opto-thermal simulation scheme is required for the investigation of the thermal limitations and optimization parameters of laser-excited remote phosphor systems, which are the next step in solid-state lighting technology.