OPTICAL ELEMENT AND SPECTROSCOPE UNIT AND POLARIZED LIGHT SEPARATING DEVICE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To solve the problem that an optical demultiplexer has to be made large-sized in order to improve the performance of the optical demultiplexer in which a diffraction grating is used because of the small wavelength dependency of emission angle from the diffraction grating. SOLUTION: In an optical element, the end face thereof nearly vertical to a layer face of a periodical multilayer structure which is deemed as a one- dimensional photonic crystal, is used as a light incident face and the surface which is in parallel with the layer face is used as a light emissive face, an affinitas band other than a lowest subsequence of the photonic crystal corresponding to a used wavelengthλ0 is utilized.