| 摘要 |
PURPOSE: To obtain a dispersion shift optical fiber which is large in a mode field diameter(MFD) and has a small nonlinear effect by adopting the constitution having a core diameter of a small diameter which is small in the value among the core diameters at which wavelength dispersion is made zero at a specific wavelength. CONSTITUTION: The outer side of a central core part 1 is provided with a staircase core part 2 and a core 3 is composed of such central core part 1 and the staircase core part 2. The outer side of the core 3 is provided with a clad 4. The core diameter (b) of the small diameter having the small value among the core diameters of the core 3 which has a staircase type refractive index distribution and at which the wavelength dispersion is made zero at the wavelength 1.55μm is selected. The core is otherwise so formed that the correction factor (k) in the relation Aeff=k.π/4.(MFD)<2> between the effective sectional area (Aeff) and MFD of the fiber attains >=0.95. The small core diameter among these core diameters (b) is adopted in such a manner, by which the correction factor (k) and the MFD are increased and further, (k) is specified to >=0.95, by which Aeff is increased and the nonlinear effect is lowered. |
