Optical fiber coupler for optimum multiplexing and demultiplexing and production of the same

TLDR: In this article, the authors proposed to improve the stability over the entire part of a system by providing the optical fiber coupler with polarization characteristics and the branching ratios to light of >= 2 specific wavelengths within a specific range, thereby making it possible to improve polarization characteristics of a fiber amplifier, to narrow the range to be controlled of a phase compensator and to obtain a stable optical output.

Abstract: PURPOSE:To improve the stability over the entire part of a system by providing the optical fiber coupler with polarization characteristics and the branching ratios to light of >=2 specific wavelengths within a specific range, thereby making it possible to improve the polarization characteristics of a fiber amplifier, to narrow the range to be controlled of a phase compensator and to obtain a stable optical output. CONSTITUTION:The polarization maintaining optical fiber 1 is formed by fusing and stretching to have the polarization characteristics and to have >=98/2 or =2 specific wavelengths. The polarization maintaining optical fiber 1 has the anisotropy of a refractive index distribution in the specific direction of the plane of polarization. The light propagation constant of the fiber varies with the one direction of the plane of polarization to be preserved and the direction of the plane of polarization orthogonal therewith. Namely, the polarization maintaining optical fiber 1 has the characteristics varying in the branching ratio to the light having the same wavelengths and the different direction of the plane of polarization by a difference in the light propagation constant depending upon the direction of the plane of polarization of the optical fiber 1, i.e., the optical fiber has the polarization characteristics.