Dispersion compensating optical fiber

#1. Field of the Invention

#The present invention relates to dispersion compensating optical fibers that are suitable for use in wavelength division multiplexing (WDM) systems, more particularly to dispersion compensating fibers that are particularly well suited for use in the C-band and L-band operating windows.

#2. Technical Background

#FIGS. 1-4 illustrate refractive index profiles of fibers made in accordance with the invention.

#FIG. 5 illustrates insertion loss as a function of wavelength for a C and L-band fiber made in accordance with the invention.

#FIG. 6 illustrates residual dispersion per unit length as a function of wavelength when a C and L band dispersion compensating fiber made in accordance with the invention are used in combination with Corning LEAF® optical fiber.

#Reference will now be made in detail to the present preferred embodiments of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. An exemplary embodiment of a refractive index profile of a fiber in accordance with the present invention is shown in FIG. 1.

#Refractive index profile 10 consists of a central up-doped region 12 having peak Δ1 which is surrounded by a first down-doped moat region 14 having peak negative A2, which is in turn surrounded by annular ring and a second up-doped region 16 having peak Δ3, all of which are surrounded by cladding region 18. Preferably, regions 12 and 16 are formed using germania doped SiO2, although other forms of index refraction increasing dopants could also be employed to achieve the fibers disclosed herein, so long as the same general refractive index profile is achieved. Likewise, whereas region 14 is preferably formed using fluorine doped SiO2, other index of refraction decreasing dopants could be employed besides fluorine. Cladding region 18 is preferably formed of silica. However, cladding region 13 could also include index of refraction increasing or decreasing in dopants, so long as the Δ versus radius relationship illustrated is maintained.

#In one embodiment of the dispersion slope compensating optical fiber illustrated in FIG. 1, Δ1 ranges between 1.0 and 2.5 percent and comprises an outer radius r1 (in FIG. 1, r1 is drawn to the point where the profile intersects the x-axis) between about 1 to 3 microns, Δ2 is less than about −0.3 percent, more preferably less than −0.4 percent, and has an outer radius r2 which ranges between about 3.5 and 8 microns, and Δ3 is between about 0.2 to 1.2 percent and comprises a center radius r3 (drawn to the center of the segment) between about 5 to 12 microns outer radius, as used herein, means the distance measured from the centerline of the optical fiber to the outer region of the segment, i.e., where the outer region of the index segment intersects the x-axis (which is also equal to the index of the cladding material 18). Center radius, on the other hand, is measured to the center of the core segment.