Sold photonic band gap fiber, fiber module using sold photonic band gap fiber, fiber amplifier, and fiber laser

摘要

A solid photonic band gap fiber includes: a core area located at a central portion of a cross-section with respect to a longitudinal direction of the fiber, the core area being formed of a solid substance having a low refractive index; cladding areas having base portions formed of a solid substance having a low refractive index, the cladding areas surrounding the core area; and a plurality of fine high refractive index scatterers provided in the cladding areas, and disposed in a dispersed manner so as to surround the core area, the number of fine high refractive index scatterers being formed of a solid substance having a high refractive index, wherein in a state that the solid photonic band gap fiber is held at a predetermined bending radius, propagation in a high-order mode is suppressed by using a difference in a bending loss between a fundamental mode and the high-order mode, and only the fundamental mode is substantially propagated, the fundamental mode and the high-order mode being caused by bending.

主权项

1. A solid photonic band gap fiber comprising:
a core area located at a central portion of a cross-section with respect to a longitudinal direction of the fiber, the core area being formed of a solid substance having a low refractive index; cladding areas having base portions formed of a solid substance having a low refractive index, the cladding areas surrounding the core area; and a plurality of fine high refractive index scatterers provided in the cladding areas, and disposed in a dispersed manner so as to surround the core area, the fine high refractive index scatterers being formed of a solid substance having a high refractive index, wherein in a state that the solid photonic band gap fiber is held at a predetermined bending radius, propagation in a high-order mode is suppressed by using a difference in a bending loss between a fundamental mode and the high-order mode, and only the fundamental mode is substantially propagated, the fundamental mode and the high-order mode being caused by bending, the high refractive index scatterers are periodically disposed in a triangular grid shape in the cladding areas surrounding the core area, at least four or more layers of the high refractive index scatterers in the periodic structure are provided in a radius direction of the fiber, when the high refractive index scatterers are assumed to be periodically disposed in a triangular grid shape toward a direction other than the radius direction from a central location of a transverse cross-section of the fiber, the core area has an area that corresponds to an area in which two or more layers of the high refractive index scatterers are removed from the central location of the transverse cross-section of the fiber, a triangular grid-shaped periodic gap between the high refractive index scatterers is in a range of 10 μm to 16 μm, and a relative refractive index difference between the high refractive index scatterers and a parent material of the cladding areas is in a range of 1.3% to 3.0%, and a predetermined bending radius is in a range of 90 mm to 200 mm, and an effective core cross-sectional area is 450 μm2 or more.