The invention discloses a compact type optical difference-frequency THz source, which comprises a dual-
wavelength laser and a difference-frequency device, wherein the dual-
wavelength laser and the difference-frequency device are sequentially arranged. The dual-
wavelength laser comprises a pump source, a laser reflective mirror, a laser
crystal, a Q switch and a laser output mirror, wherein the above parts are arranged in turn. The difference-frequency device comprises a laser focusing lens and a difference frequency
crystal, wherein the laser focusing lens and the difference frequency
crystal are arranged in turn. The pump laser emitted by the pump source is injected into the laser crystal. Through the
energy level transition process, activated particles inside the laser crystal are transited into the upper level to generate the
laser oscillation inside an oscillation cavity formed by the laser reflective mirror and the laser output mirror. The laser crystal is composed of two crystals used for generating the
laser oscillation at two wavelengths. By means of the Q switch, the loss of the oscillation cavity is adjusted, so that the pulse laser can be outputted. The outputted laser is injected into the difference frequency crystal after being focused through the laser focusing lens to generate the difference
frequency effect, generate and output terahertz
waves. The compact type optical difference-frequency THz source is compact in structure, and can be applied to small-cost, miniaturized and portable demand scenarios.