A QUASI-SINGLE MODE OPTICAL-FIBER FOR LONG-HAUL TRANSMISSION IN SEVERE BENDING ENVIRONMENTS

We investigated the feasibility of a quasi-single mode optical fiber for low bending losses in long-haul transmission at 1550 rum. The advantage of a quasi-single mode fiber is that for comparable bending losses the relative index difference, DELTA, can be smaller than the DELTA in a single-mode fiber. We demonstrated that a quasi-single mode fiber with DELTA = 0.72% and single-mode cutoff wavelength, lambda(c), equal to 1630 nm exhibits bending losses as low as the losses in a single-mode fiber with DELTA = 0.93% and lambda(c) = 1259 nm. Modal noise and modal dispersion effects in the quasi-single mode fiber also were tested and found to be minimal. This letter describes the matched-clad, quasi-single mode fiber and presents the test results.