| 摘要 |
PURPOSE:To realize a long-distance and large-capacity transmission system using the light source having extension of the wavelength, by securing a mutual negative between the material diffusion and the mode diffusion and then reducing the limitation of the transmission band. CONSTITUTION:In order to secure a mutual negation between the difference of group delay time due to the material diffusion at the light source and the group delay time due to the mode diffusion of the optical fiber, the fiber of distribution type of alphaapprox.=4 or alphaapprox.=1 (alpha: distribution from of refractive index) to give the former the high-order mode excitation and low-order mode excitation for the beams of the long and short wavelength sides each. And vice versa for the latter. Then the beams sent from the light source 5 are condensed 4 and then put into the prism 6 to cause a difference by deltatheta to the radiation angle theta according to the wavelength under a constitution including the optical fiber core 1, cladding 2, condenser lenses 3 and 4, light source 5 and branching prism 6 each. The beams thus condensed are then reduced the aperture through the lens 3, and then the beam of the long wavelength side is reduced the operature at the outer circumference part to the fiber of alphaapprox.=4. Thus the diffusion can be negated. |
