Compact and portable terahertz source by mixing two frequencies generated simultaneously by a single solid-state laser

We have demonstrated a compact and portable terahertz (THz) source, based on difference-frequency generation in a GaSe crystal. The two input frequencies, required for achieving frequency mixing, are generated by a single Q-switched Nd:YLF laser incorporating two laser resonators. The average power of the THz output reaches 1 μW at 1.64 THz (182 μm) within a linewidth of 65 GHz. Such a THz source can be packaged into a compact and portable system.