An optical irradiation device for the polarization of alkali metal atoms for the hyperpolarization of noble gases by spin exchange includes at least one semiconductor laser device which can generate laser light which, with regard to its wavelength, is suitable for the polarization of the alkali metal atoms. A polarizer effects circular polarization of the laser light generated by the semiconductor laser device. A device for introducing the laser light into a working region in which the alkali metal atoms to be polarized can be present, and a device for defining a wavelength of the laser light, which can couple part of the laser light back into the semiconductor laser device in order thereby to define the wavelength of the laser light at a predetermined wavelength or a predetermined wavelength range.