[信息与通信]光纤通信基础知识培训.ppt

纤芯的变化 Off Center Different Size Non-Circular Off Center, Different Size, Non-Circular “Perfect” Fiber These two fibers will NEVER be spliced together without loss. Core 弯曲损耗 宏弯：可见的弯曲，由于超过了标准的角度，会引起光的放射 波长越长就越严重 微弯：通过显微镜才能看到的完全，由于生产或温度等原因引起的 Absorption Loss Microbending Loss Macrobending Loss 连接器 典型的衰耗值在0.10dB 和0.25dB之间 纤芯不匹配引起的接续损耗 由于纤芯直径的偏移，第二根光纤并没有接收到所有来自第二根光纤的光。丢失掉的光称为熔接损耗。 典型的熔接损耗值 熔接: 0.05 to 0.20 dB 机械: 0.10 to 0.50 dB 熔接损耗倚赖下列因素: 光纤的质量 工艺 熔接设备的质量 连接器损耗 End-Face Separation Angular Separation Core Misalignment 典型损耗 = 0.5dB 光纤色散 什么是色散? 光脉冲在通过光纤传播时的脉冲的扩展或展宽 色散太大会引起接收端的误码 0 1 0 0 1 0 1 1 0 0 1 1 0 1 1 1 1 1 原始信号 不同的延迟 Bit Errors 色散的类型 模式色散 在多模光纤中，由于不同模式的光纤通过的路径长度不相同引起的。 色度色散 由光源的非零频谱带宽引起的，不同的波长以不同的速度传播 偏振模式色散 由正交偏震模式的两个激化模式在光纤中不同的传播速度引起的。 Multimode fiber (Step Index) ?1 ?2 SMF SMF 3.问题？ 谢谢！ Section 1: Definition and Advantages of Fiber Optics When used for communication purposes, information can be transmitted on the light which is sent through the transparent fibers. An optical transmitter is simply a source of light, such as a light bulb. An electrical signal such as a voice, data, or video transmission, is converted to light by using the electrical signal to turn the light on and off (for a digital signal), or to vary the intensity of the light (for an analog signal). In a digital signal, the presence of light is a “1” and the absence of light is a “0”. In an analog signal the intensity of the light matches the strength of the electrical signal level. It is like blinking a flashlight to signal someone across the street, or like using the dimmer on your dinning room light to brighten or darken the room. A basic fiber optic link can be 100 feet long or 1000 miles long. The elements are the same: All have a transmitter (abbreviated as “TX”), a receiver (abbreviated as “RX”), and one or more sections of fiber between the two. With more than two fiber sections, their will be in-line splices. In very long systems the signal may nee