THz radiation promises to revolutionise applications in fields from security and counter terrorism, to medicine and agriculture. In the drive to develop robust, powerful and frequency-tunable THz laser sources, systems based on the stimulated polariton scattering (SPS) process, derived from solid state architectures, are arguably at the forefront [1–3]. Within the realm of THz-SPS lasers, there are significant opportunities to enhance the performance of these systems, through careful consideration of the system architecture.