| 摘要 |
PURPOSE: To transmit output light particularly with good gauss mode and to simplify production by specifying the refractive index distribution in a core, thereby holding the mode structure of the light injected into a fiber in the output light as far as pos sible. CONSTITUTION: This optical fiber has the core of a diameter DK, a clad around the core and a protective sheath around the clad and the refractive index distribution in the core complies with the index rule expressed by equation I. In the equation I, γ denotes the distance from the axial center of the fiber; nki denotes the refractive index of the axial core; nRa denotes the refractive index of the core on the boundary of the clad. The fiber satisfies the following conditions. Namely, the diameter DK of the core is required to be 200.10<-6> to 8000.10<-6> m. However, DR is 2.5 times the equation II and θ' is 5 in the case of the max. order mode θ of laser radiations below 5, θ':θ in the case of θ 5 to 20 and θ' is the value of equation III in the case of θ>=20. ΔnK. Denotes the refractive index difference in the core and λ denotes the wavelength of the laser radiations to be transmitted. An index (g) is required to be 1.4 to 3.0 and ΔnK=nRi -nRa is required to be larger than 1.6.10<-3> . |
