PURPOSE: To provide a second harmonic generation device having a stable wavelength control performance by constituting an external resonator only with a diffraction grating and a semiconductor laser.
CONSTITUTION: A beam from the semiconductor laser 1 is splitted by a beam splitter 2, and one of the beam is guided to a second harmonic element 4, and a wavelength is selected by constituting the external resonator constituted of the diffraction grating 5 and the semiconductor 1 with the other. The beam emitted from the semiconductor laser 1 is made parallel beams by a lens 7, and the parallel beams are made incident on the Littrow-mounted diffraction grating 5 from the beam splitter 2 reflecting and splitting 30% or more of it. A first-order reflection beam by the diffraction grating 5 is returned to the semiconductor laser 1 through the same optical path. The second harmonic 6 is generated by adjusting an angle of the diffraction grating 5 so that the wavelength of a basic wave coincides with a phase matching wavelength corresponding to a period of a polarization inversion grating 12.
NITANDA FUMIO
ITOU AKITOMO
KOMODA MIGAKU
KAWAMOTO KAZUTAMI
HITACHI LTD
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