Patent ID: 7356234

Claim:
A dispersion compensating optical fiber, comprising: a central core surrounded by an external optical cladding, said central core having a radius r 1 and a refractive index difference Dn 1 with said external optical cladding; an intermediate cladding positioned between said central core and said external optical cladding, said intermediate cladding having a radius r 2 , a width (r 2 âˆ’r 1 ) greater than or equal to about 2.0 microns, and a refractive index difference Dn 2 with said external optical cladding; and a depressed inner cladding positioned between said intermediate cladding and said external optical cladding, said inner cladding having a radius r 3 and a refractive index difference Dn 3 with said external optical cladding, the refractive index difference Dn 3 being less than or equal to about âˆ’3.0Ã—10 âˆ’3 , wherein at a wavelength of 1550 nm, the optical fiber has a positive chromatic dispersion greater than or equal to about 21 ps/(nmÂ·km) and a ratio of the mode radius of the fundamental mode LP01 propagating in the optical fiber (W 02 ) over the radius of the intermediate cladding (W 02 /r 2 ) less than or equal to about 0.7.