通信工程专业英语第6节.ppt

For a fiber (designed to carry light in several modes of n. 模式 propagation at the same time (called a multimode n. 传播 fiber)), the diameter of the core is several times the 多模光纤 n. 直径 wavelength (of the light (to be carried)). n. 波长 能够同时携载多个传输模式的光纤（称作多模光纤），其纤芯直径是所携载波长的几倍。 * * Wavelength is a measure (of the distance (between two n. 波长 n. 测量 cycles (of the same wave))) (measured in nanometers, n. 周期 vt. 测量 n. 纳米 or billionths of a meter), and the cladding thickness n. 十亿分之一 n. 包层 n. 厚度 will greater than the radius of the core. 大于 n. 半径 波长是同一个光波2周之间距离的量度标准，以纳米即一米的十亿分之一来表示，光纤包层厚度要大于光纤纤芯的半径。 * * A light source emits light (at many angles relative to the vt. 发射 相对于 center of the fiber). In Fig.2, light ray A enters the vt. 进入 fiber perpendicular to the face of the core and parallel adj. 垂直的 n. 表面 adj. 平行的 to the axis. 光源在相对于光纤中心的多个角度发射出光线。在图2中可以看到，光线A沿垂直于纤芯表面的方向射入光纤，光线与光纤轴平行。 * * For optical fibers (in which the diameter of the core is n. 直径 many times the wavelength of the light (transmitted)), n. 波长 the light beam travels along the fiber by bouncing n. 横梁(光束) vi. 弹跳 back and forth at the interface between the core and 反复低 接口 the cladding. 对于纤芯直径是光波长几倍的光纤，光束通过在纤芯和包层界面处来回反射而沿着传播。 * * Rays (entering the fiber at differing angles) are vt. 进入 refracted (varying numbers of times)