OPTICAL ELEMENT, SPECTROSCOPE, AND CONDENSER

摘要

In a photonic crystal (1), the sizes of air holes (3) are gradually changed along the z-axis, while the refractive index of the medium (2) and the period of the lattice are constant. A light (4) having a frequency of around 0.61 travels almost straightforward upon the incidence on the crystal, and however the direction of travel changes as the size of the hole becomes smaller. The optical path of a light bends greatly as indicated by the numerals 5 and 6 as the frequency becomes greater. Accordingly, a light within a narrow range of wavelength is refracted with a great refraction angle, and the light can be dispersed with a good resolving power.