| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to evade the influence of an optical nonlinear phenomenon and the influence of material dispersion by providing the optical fiber with a core having a region of about several times of the wavelength of light and a clad having a diffraction grating of an inter-grating pacing equal to half the wavelength of the light. SOLUTION: This optical fiber has the core 1 having the region of about several times of the wavelength of the light and the clad 2 which is arranged around the core 1 and is provided with the diffraction grating having the inner- grating pacing equal to half the wavelength of the light in at least a circumferential region adjacent to the core 1. The core 1 is a hole and the refractive index thereof is equal to the refractive index of air and is nearly 1. The core 1 formed of the hollow hole is free from a factor to scatter the light and is, therefore, most preferable. The circumferential region adjacent to the core 1 is provided with the diffraction grating having the inter-grating pacing equal to half the wavelength of the light. Namely, the optical fiber is provided with a photonic band gap structure over a diameter 2b. The light may be confined and propagated in the core 1 in such a manner that the light does not propagate in the radial direction from the center of the core 1 of the optical fiber. |
