A compact stabilized three-laser optical pump system for an imaging system based on THz-to-visible conversion via atomic vapour

THz imaging often struggles to achieve necessary framerates for applications, but recent demonstrations show that an imaging system based upon THz-to-optical conversion in atomic vapour can provide ultrahigh speeds while retaining sensitivity with optical cameras. This atomic vapour imaging requires a multi-frequency near-IR optical pumping system, and we demonstrate a compact system to provide the stable frequencies required for conversion of 0.55 THz light to visible (green) in caesium atoms. Through the integration of distributed feedback (DFB) laser diodes and a compact extended cavity diode laser, and spectroscopy and offset locks based on open-source FPGA and Arduino code, it approaches suitability for wider industrial application.