OPTICAL FIBER WITH A LOW-INDEX CORE AND A CORE GRATING

摘要

An optical fiber with a low-index core and a core grating has a solid and generally cylindrical annular cladding having a refractive index n_cl, a central axis, an inner surface with a radius r wherein r≧2 μm, an outer surface with a radius R, and an annular thickness ΔR≧10 μm. The fiber core has the radius r and a refractive index n_c, wherein n_cln_c. The grating is defined by grating elements that extend from the cladding inner surface into the core and that run generally parallel to the central axis. The grating elements define a period , a width t, a spacing a and a height h, wherein 0.5/λ1 and wherein 0.2≦t/a≦3.