FIBER TYPE WAVELENGTH FILTER

摘要

PURPOSE:To provide a titled filter which is small in size, is highly flexible and is easily connectable to optical fibers by fully constituting the wavelength filter of optical fibers. CONSTITUTION:The fiber type wavelength filter is formed by successively connecting the dual-core fibers 15 each of which has the 1st core 16 at the center of the clad and the 2nd core 17 in the offcentered position of the clad and satisfies cl1=mpi (c; coupling constant at the wavelength lambda0 of the dual-core fiber, l1; length of the shortest dual-core fiber, m; positive integer). The length ln of the n-th dual-core fiber satisfies ln=2l1 (n; 1-N integer, N; the number of the dual-core fibers). The direction where the 1st core and the 2nd core of the n-th dual-core fiber are connected is designated as Xn axis and the respec tive 1st cores of the n-th and (n+1)th dual-core fibers are so connected to each other by rotating the Xn axis and Xn+1 axis as not to induce the optical cou pling. The terminal of the N-th dual-core fiber is a single mode fiber having only the 1st core.