Dispersion managed fiber

An optical fiber preform for making a dispersion managed optical fiber, comprising:

• a central core glass or soot region having a first refractive index profile, a delta percent of said central core glass region comprises up to about 1.1%;
• and
• a second core glass region adjacent to and surrounding said central region, said second region having a thickness that varies along an axial direction of said second region, having a second refractive index profile that differs from said first profile, and a delta percent of said second core glass region comprises no lower than about −0.6%.

A method of making an optical fiber preform for making a dispersion managed optical fiber, comprising the step of:

• inserting a rod of a material for forming a glass region, having a first refractive index profile into a glass tube having a varying wall thickness in an axial direction of the tube and the tube having a second refractive index profile that differs from the first profile, wherein a delta percent of the rod comprises up to about 1.1% and a delta percent of the tube comprises no lower than about −0.6%.

An optical fiber preform assembly for making a dispersion managed fiber comprising:

• a rod of a material for forming a glass region, having a first refractive index profile and a delta percent up to about 1.1%;
• a glass tube having a varying wall thickness in an axial direction of the tube and the tube having a second refractive index profile that differs from the first profile and delta percent of no lower than about −0.6%, said tube having an interior surface adjacent and exterior surface of said rod.