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 nm. The advantage of a quasi-single mode fiber is that for comparable bending losses the relative index difference, /spl Delta/, can be smaller than the /spl Delta/ in a single-mode fiber. We demonstrated that a quasi-single mode fiber with /spl Delta/=0.72% and single-mode cutoff wavelength /spl lambda//sub c/ equal to 1630 mn exhibits bending losses as low as the losses in a single-mode fiber with P=0.93% and /spl lambda//sub 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.<
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