Abstract: The invention relates to a low dispersion slope dispersion-shifted single-mode fiber for large capacity transmission comprising a core and a cladding. Said fiber is characterized in that said core has three to five core segments having different refractive index profiles, and said cladding has four to six cladding segments. The total dispersion slope of said fiber at 1550 nm is less than 0.060 ps/nm2·km, the zero dispersion wavelength is less than 1420 nm, the effective area ranges from 55 ?m2 to 65 ?m2, and the dispersion in the region of 1530 nm˜1565 nm ranges from 5.0 ps/nm2·km to 12.0 ps/nm2·km. The fiber has low dispersion slope, moderate dispersion, low attenuation, and excellent bend resistance performance. It is suitable for a high-speed (10 Gbits/s and 40 Gbits/s), large capacity, and long distance DWDM system.

Abstract: Columnar pillars are arranged in a square lattice pattern to form a two-dimensional photonic crystal. The two-dimensional photonic crystal has crystal defects created by the absence of pillars, and a resonator is formed in a line waveguide provided by the crystal defects. The resonator is made up of a main pillar, a pair of sub-pillars disposed at the light incidence side of the waveguide with respect to the main pillar and another pair of sub-pillars at the light emitting side of the waveguide with respect to the main pillar, the main pillar and sub-pillars being disposed in the waveguide. The main pillar and the sub-pillars are formed of the same medium as that of the pillars, and are formed simultaneously with the pillars by patterning a silicon thin film coated all over a silicon substrate through a SiO2 film formed over the entire surface thereof. Light of a particular wavelength in wavelength-multiplexed incident light is transmitted through the resonator.