Patent ID: 8145025

Claim:
A single-mode optical fiber, comprising: a central core surrounded by an outer optical cladding, the central core having a radius r 1 and a positive refractive index difference Δn 1 with the outer optical cladding; an intermediate cladding positioned between the central core and the outer optical cladding, the intermediate cladding having a radius r 2 and a positive refractive index difference Δn 2 with the outer optical cladding, wherein the refractive index difference Δn 2 is less than the refractive index difference Δn 1 ; and a depressed trench positioned between the intermediate cladding and the outer optical cladding, the depressed trench having a radius r 3 and a negative refractive index difference Δn 3 with the outer optical cladding; wherein, at a wavelength of 1310 nanometers, the optical fiber has a nominal mode field diameter (MFD) between 8.6 microns and 9.5 microns; wherein, at a wavelength of 1550 nanometers, the optical fiber has bending losses less than 0.25×10 −3 dB/turn for a radius of curvature of 15 millimeters; and wherein, at a wavelength of 1260 nanometers, the LP11 mode of the optical fiber is attenuated to 19.3 dB at a length less than 90 meters.