A laser device for emitting waves within a frequency range comprised between 0.5 THz and 5 THz comprising a semiconductor heterostructure having a substantially cylindrical shape with a circular cross-section, said heterostructure comprising: - a first layer of an optically nonlinear semiconductor material including emitting means (110, 111) able to emit in at least two optical whispering gallery modes belonging to the near infrared, said at least two whispering gallery modes being confined in said first layer and enabling, within said first layer a radiation to be generated in an electromagnetic whispering gallery mode with a frequency comprised between 0.5 THz and 5 THz, called Terahertz mode, said radiation being generated by the difference in frequency of said two whispering gallery modes, the substantially cylindrical geometry of said heterostructure ensuring the phase matching between the two optical whispering gallery modes belonging to the near infrared and the Terahertz mode at the difference in frequency; - a second and a third layers of semiconductor material each having a lower optical index than the index of the material used for said first layer and located on either side of said first layer; - at least one metal layer (103, 104) located at one end of said heterostructure; said device being characterised in that: - said heterostructure is provided at the centre thereof with a hole having a substantially cylindrical shape extending along the whole height (h) of said heterostructure, the radius of said hole being selected in order to enable the phase matching to be established; - the difference between the radius (R ext) of the cylinder forming said heterostructure and the radius (Pint) of the hole is greater than 0, 05 x λ T H z η T H z, where λ THz is the emission wavelength in the frequency range comprised between 0.5 THz and 5 THz and η THz is the effective propagation index of the Terahertz mode at the wavelength λ THz; - the device comprises a setting element made of a low absorbing material in the frequency range comprised between 0.5 THz and 5 THz, said setting element having a size smaller than that of said hole and being inserted in said hole. - a first layer of an optically nonlinear semiconductor material including emitting means (110, 111) able to emit in at least two optical whispering gallery modes belonging to the near infrared, said at least two whispering gallery modes being confined in said first layer and enabling, within said first layer a radiation to be generated in an electromagnetic whispering gallery mode with a frequency comprised between 0.5 THz and 5 THz, called Terahertz mode, said radiation being generated by the difference in frequency of said two whispering gallery modes, the substantially cylindrical geometry of said heterostructure ensuring the phase matching between the two optical whispering gallery modes belonging to the near infrared and the Terahertz mode at the difference in frequency; - a second and a third layers of semiconductor material each having a lower optical index than the index of the material used for said first layer and located on either side of said first layer; - at least one metal layer (103, 104) located at one end of said heterostructure; - said heterostructure is provided at the centre thereof with a hole having a substantially cylindrical shape extending along the whole height (h) of said heterostructure, the radius of said hole being selected in order to enable the phase matching to be established; - the difference between the radius (R ext) of the cylinder forming said heterostructure and the radius (Pint) of the hole is greater than 0, 05 x λ T H z η T H z, where λ THz is the emission wavelength in the frequency range comprised between 0.5 THz and 5 THz and η THz is the effective propagation index of the Terahertz mode at the wavelength λ THz; - the device comprises a setting element made of a low absorbing material in the frequency range comprised between 0.5 THz and 5 THz, said setting element having a size smaller than that of said hole and being inserted in said hole.