Patent ID: 8145027

Claim:
A bend-insensitive optical fiber, comprising: a single-mode glass fiber comprising (i) 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; (ii) an intermediate cladding positioned between the central core and the outer optical cladding, the intermediate cladding having a radius r 2 and a 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 (iii) 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; and a substantially cured primary coating surrounding the single-mode glass fiber, the substantially cured primary coating possessing (i) an in situ modulus of less than about 0.65 MPa and (ii) a glass transition temperature of less than about −50° C.; 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 0.15 dB/turn for a radius of curvature of 5 millimeters; and wherein the optical fiber has a cable cut-off wavelength (λ cc ) of 1260 nanometers or less, measured as the wavelength at which the attenuation of the LP11 mode is greater than or equal to 19.3 dB after propagation over 22 meters of fiber.