| 摘要 |
PROBLEM TO BE SOLVED: To obtain a multidimensional diffraction grating capable of simply obtaining nearly an equal effect to a photonic crystal by constituting a diffraction grating out of a substance of which the refractive index is changed by irradiation of an electromagnetic wave or electron beam, and multidimensionally and periodically forming territories of different refractive indexes therein. SOLUTION: Two beams of a laser beam 1 are oppositely made incident to a CdF2: Ga crystal 2, territories of different refractive index are periodically formed, to write one-dimensional diffraction grating 3 therein. The period of the written diffraction grating is decided by the wavelength of the laser beam 1, for example, in the case of the wavelength of 514.4 nm of an argon laser, it is 164 nm. Next, as shown in Fig. b, the CdF2: Ga crystal 2 is rotated by 90 deg., to write the diffraction grating 3 also in the cross direction at right angles to the previously written diffraction grating 3 as shown in Fig. c, and obtain the two-dimensional diffraction grating. Next as shown in Fig. d, the CdF2: Ga crystal 2 is further rotated by 90 deg., to write the diffraction grating 3 in the cross direction at right angles to the diffraction grating 3 as shown in Fig. e, to obtain three-dimensional diffraction grating.
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