Abstract: A method of connecting a holey fiber to an optical fiber includes fusion splicing an end surface of the holey fiber and an end surface of the optical fiber thereby forming a joint section; and stretching the joint section while heating by pulling the holey fiber and the optical fiber away from each other in a longitudinal direction until an outer diameter of the joint section attains a predetermined value.

Abstract: A silica-based optical fiber includes a core and a cladding that is formed on an outer circumference of the core. The core includes three or more layers including a layer doped with at least one of germanium and fluorine, and a concentration of the germanium or the fluorine in each of the layers is controlled in such a manner that a Brillouin gain spectral peak is spread into a plurality of peaks on a Brillouin gain spectrum. With this scheme, an optical fiber is provided, which has stable characteristics in the longitudinal direction, and which has a high SBS threshold so that generation of the SBS can be effectively suppressed.

Abstract: A holey fiber, which has a zero-dispersion wavelength of less than 700 nm and operates as single mode under its zero-dispersion wavelength, is provided. The holey fiber according to the present invention comprises a core region that is formed at a center of the holey fiber; and a cladding region, formed at the circumference of the core region, which has a plurality of holes distributed as triangle lattice around the core region; wherein the holey fiber has a fundamental mode of less than 700 nm, a higher order mode, and the fundamental mode and the higher order mode confinement losses of less than 0.1 dB/m and more than 10 dB/m, respectively, at the zero-dispersion wavelength.

Abstract: A photonic bandgap fiber includes a hollow core formed along a center axis of the photonic bandgap fiber, through which a light propagates and a cladding region made of silica glass. The cladding region includes air holes forming a triangular lattice arranged around the hollow core. A lattice constant of the triangular lattice of the air holes ? is equal to or smaller than 2.1 ?m. Confinement loss in a predetermined wavelength range including a center wavelength of a photonic bandgap is lower than scattering loss.

Abstract: A method of connecting a holey fiber to an optical fiber includes fusion splicing an end surface of the holey fiber and an end surface of the optical fiber thereby forming a joint section; and stretching the joint section while heating by pulling the holey fiber and the optical fiber away from each other in a longitudinal direction until an outer diameter of the joint section attains a predetermined value.

Abstract: An optical fiber transmits at least a signal light having a wavelength of 1550 nanometers in a fundamental propagation mode. The optical fiber has, a cutoff wavelength equal to or longer than 1550 nanometers, a wavelength dispersion of 4 ps/nm/km to 7 ps/nm/km in the fundamental propagation mode at the wavelength of 1550 nanometers, a dispersion slope of a positive value equal to or smaller than 0.03 ps/nm2/km in the fundamental propagation mode at the wavelength of 1550 nanometers, an effective core area equal to or larger then 60 ?m2 in the fundamental propagation mode at the wavelength of 1550 nanometers, and a bending loss equal to or smaller than 20 dB/m with a winding of 16 turns at a diameter of 20 millimeters in the fundamental propagation mode at the wavelength of 1550 nanometers.

Abstract: An optical fiber transmits at least a signal light having a wavelength of 1550 nanometers in a fundamental propagation mode. The optical fiber has a cutoff wavelength equal to or longer than a wavelength of 1550 nanometers, a wavelength dispersion in the fundamental propagation mode at the wavelength of 1550 nanometers larger than 0 ps/nm/km, and a dispersion slope in the fundamental propagation mode at the wavelength of the signal light equal to or smaller than ?0.05 ps/nm2/km.

Abstract: An optical fiber that transmits a signal light in a fundamental propagation mode has a cutoff wavelength longer than a wavelength of the signal light, a wavelength dispersion of the fundamental propagation mode of ?5 ps/nm/km to ?1 ps/nm/km at a wavelength of 1550 nanometers, an effective core area of the fundamental propagation mode larger than 45 ?m2 at the wavelength of 1550 nanometers, and a dispersion slope of the fundamental propagation mode smaller than 0.03 ps/nm2/km at the wavelength of 1550 nanometers.

Abstract: An optical fiber transmits at least a signal light having a wavelength of 1550 nanometers in a fundamental propagation mode. The optical fiber has, a cutoff wavelength equal to or longer than 1550 nanometers, a wavelength dispersion of 4 ps/nm/km to 7 ps/nm/km in the fundamental propagation mode at the wavelength of 1550 nanometers, a dispersion slope of a positive value equal to or smaller than 0.03 ps/nm2/km in the fundamental propagation mode at the wavelength of 1550 nanometers, an effective core area equal to or larger then 60 ?m2 in the fundamental propagation mode at the wavelength of 1550 nanometers, and a bending loss equal to or smaller than 20 dB/m with a winding of 16 turns at a diameter of 20 millimeters in the fundamental propagation mode at the wavelength of 1550 nanometers.

Abstract: With this scheme, there is provided an optical communication system and a dispersion-compensating optical fiber with which a long-haul optical signal transmission is possible by making use of the low optical nonlinearity and the low transmission loss characteristic of the photonic bandgap optical fiber.