Patent ID: 7978947
Filing Date: 2011-07-12
Classification: G02B,H01S

Abstract:
1. A photonic bandgap fiber comprising: a first core having a refractive index equal to or smaller than a refractive index of a cladding; a second core that is provided to surround the first core and has a refractive index smaller than the refractive index of the first core; the cladding that surrounds the second core; and a periodic structure portion that is provided in the cladding around the second core, and in which high-refractive index portions having a refractive index larger than the refractive index of the cladding form a periodic structure, wherein the periodic structure is configured such that at least the propagation constant of the fundamental mode at a wavelength to be used is in a photonic bandgap, and the propagation constant of a higher-order mode at the wavelength to be used is outside of the photonic bandgap.