A laser device for emitting waves in a frequency range belonging to the terahertz range, includes the following, in combination: a wave guide extending longitudinally along an axis A-A′; a superconducting coil arranged coaxially to the wave guide and arranged at a first end of the wave guide; a p-Ge p-doped germanium crystal arranged inside the coil such that the turns of the superconducting coil at least partially surround the p-Ge crystal; a cooling device containing a coolant, the superconducting coil and the p-Ge crystal being arranged in the cooling device, and the wave guide partially extending outside the cooling device; and removing the coolant from the wave guide.