SINGLE MODE PHOTONIC CRYSTAL OPTICAL FIBER

摘要

A clad part (12) arranged periodically with a plurality of columnar voids (14) having a diameter d at a central interval Lambda is provided around a core part (11) having a geometrical diameter rho where the central interval Lambda of the voids (14) is set not shorter than 1.5 times the wavelength lambda of a propagation light and a value V determined according to a following expression is set between 2.4 and 3.3. At least one of the geometry of the voids (14) at the clad part (12) and the optical constant distribution of the clad part (12) or the core part (11) is set less than trigonal-axis symmetry with respect to the central axis of the core part (11), thus releasing polarization degeneracy of the propagation light. V=2pirho(n<2>core-n<2>eff)<1/2>/lambda (neff: effective refractive index at the clad part, ncore: refractive index at the core part).