Patent ID: 7177512

Claim:
An optical fiber, comprising: a centermost laterally-elongated core including a first refractive index (n 1 ), said centermost laterally-elongated core having a short dimension (a) and a long dimension (b), a moat surrounding having a second refractive index (n 2 ) and abutting the central laterally-elongated core, an outer dimension (c) along an axis X—X aligned with the long dimension (b), and an outer dimension (d) along an axis Y—Y aligned with the short dimension (a) wherein the axis X—X is generally orthogonal with the axis Y—Y, and a cladding surrounding the moat, the cladding having a third refractive index (n 3 ), wherein n 1 >n 3 >n 2 , a ratio of b/a is between 1.5 and 5.0, a ratio of d/a is between 2.0 and 7.0, and the optical fiber exhibits (i) single polarization propagation within a single polarization band and (ii) polarization maintaining property, such that the fiber beat length normalized at 1550 nm to be less than 10 mm, and polarization maintaining band PMB is situated at wavelengths below the single polarization band and above the higher order mode cutoff wavelength.