Design Consideration on Broad-Band W-Type Two-Mode Optical Fibers

Structural design for broad-band W-type two-mode optical fibers is investigated. The optimum parameters are numerically determined as follows: the operating V-value with zero group delay time difference Delta lambda between the LP ₀₁ and LP ₁₁ modes is 6.7, the ratio of core radius to inner cladding radius is 0.6, and the index profile parameter is 2.02. then, the core radius is 12.3 µm for Delta=0.3 percent at the operating wavelength of 1.3 µm. The V-value deviation tolerance from the optimum to maintain Delta lambda less than +-20 ps/km is 21 percent, which is 20 times larger than that of the earlier design made on two-layer index profile.