A new type of doubly clad single-mode fiber has been fabricated through the MCVD process, Design criteria with due regard to fabrication conditions that optimize fiber structure have also been investigated. As a result of determination of these criteria, a dispersion-minimized single-mode fiber with an index difference between core and outer cladding Δ
1equal to 0.52 percent, an index difference between outer and inner cladding Δ
2equal to -0.31 percent, a core diameter

m, and

has been fabricated. The absolute value of the total dispersion of the fiber has been reduced to within ± 1 ps/km/nm in the

m spectral range.