The invention relates to a device for controlling route of a single photon belonging to the area of aquanta security communication technique. The device consists of a M-Z (Mach-Zehnder) interferometer and a optical phase modulator. The M-Z interferometer is composed of the spectroscope 1,3 and the holophote 2,4. The splitting ratio of the spectroscope 1,3 is 50%. The holophote 2,4 is of total reflection on a single photon wavelength. The optical phase modulator includes the holophote 2 and the piezo-electric micro displacement meter, i.e. the micro displacement of the PZT controls the phase modulation. The input end 6 is the input end of the control voltage of the displacement meter 5. The optical phase modulator can be an Electro-Optical phase modulator i.e. EOM positioned between the spectroscope 1 and the holophote 2.