The invention discloses a terahertz wave switch device and a method thereof. The terahertz wave switch method comprises the following steps that: when a
magnetic field device is provided with no external
magnetic field, terahertz wave is input from a terahertz wave input end, vertically enters the lower bottom surface of an isosceles trapezoidal
glass prism from the side surface of a short side of a rectangle on the lower bottom surface of the isosceles trapezoidal
glass prism, is vertically output to a first terahertz wave output end after being reflected, and a terahertz wave
detector detects the output terahertz wave; and when the
magnetic field device is provided with an external magnetic field, the magnetic permeability of a magnetic film is changed, an
optical path is shifted, the terahertz wave is reflected on the lower bottom surface of the isosceles trapezoidal
glass prism and is vertically output to a second terahertz wave output end, and the terahertz wave
detector cannot detect the output terahertz wave at this time. The terahertz wave switch device has the advantages of compact structure, high response speed, convenient adjustment and low manufacturing cost, and meetsthe requirements on the application in terahertz wave imaging,
medical diagnosis, terahertz wave communication, terahertz wave space
astronomy and other fields.