Patent ID: 7865050

Claim:
A multi-mode optical fiber comprising in cross section: a. a core with a material having a predetermined refractive index b. a first cladding surrounding and in contact with the core, the first cladding having a refractive index less than that of the core, c. a second cladding surrounding the first cladding the second cladding having a refractive index less than that of the first cladding, d. a third cladding surrounding the second cladding the third cladding having a refractive index approximately that of silica, the optical fiber having: near equalized modal delays for all guided modes with effective index larger than the refractive index of cladding d, and bending loss less than 0.1 dB/turn with â‰¦10 mm bending diameter and less than 0.3 dB/turn with â‰¦5 mm bending diameter when coupled to a 10 Gigibit or higher bit rate VCSEL at 850 nm, the optical fiber having the refractive index profile: n â¡ ( r ) - n clad n clad = â¢ Î” â¡ ( 1 - ( r r core ) a ) â¢ for â¢ â¢ r â‰¤ r 0 â‰¤ r core = â¢ Î” 1 â¢ for â¢ â¢ r 0 < r â‰¤ r tr â¢ â¢ 1 = â¢ Î” 2 â¢ for â¢ â¢ r tr â¢ â¢ 1 < r â‰¤ r tr â¢ â¢ 2 = â¢ 0 â¢ for â¢ â¢ r â‰¥ r tr â¢ â¢ 2 where n(r) is absolute refractive index at radial position r, n clad is absolute refractive index of cladding, r is radial position, Î”, Î” 1 , Î” 2 are relative index difference and r core is core radius, and Î± preferably has a value of 1.9 to 2.2.