光纤通信 1.Fiber Optic Communications System.ppt

Fiber Optic Communications Fiber Optic Communications Chapter 1: Fiber Optic Communication Systems Chapter 2: Optics Review Chapter 3: Lightwave Fundamentals Chapter 4: Integrated Optic Waveguides Chapter 5: Optic Fiber Waveguides Chapter 6: Optical Source and Amplifiers Review Chapter 1 Fiber Optic Communications System Chapter 1 Fiber Optic Communications System Chapter 1 Fiber Optic Communications System Please read the paragraphs from “light was always been with us ” to “In fact, any type of indicator lamp is basically an optic communications system ” When you are reading, please think about two questions: How many kinds of traditional communication systems it has introduced? 2. what’s the common disadvantage of these communication systems? During the day, the sun is the source of light for this system. The information is carried from the sender to the receiver on the sun’s reflected radiation. Hand motion modifies, or modulates, the light. The eye is the message-detecting device, and the brain processes is this message. Information transfer by such a system is slow, the transmission distance is limited, and the chances for error are great. A later optic system, useful for longer transmission paths, was the smoke signal. The message was sent by varying the pattern of smoke rising from a fire. This pattern was again carried to the receiving party by reflected sunlight. This system required that a coding method be developed and learned by the communicator and receiver of the message. This is comparable to modern digital systems that use pulse codes. It used sunlight reflected from a thin voice-modulated mirror to carry conversations. At the receiver, the modulated sunlight fell on a photo-conducting selenium(硒) cell, which converted the message to electrical current. A telephone receiver completed the system. The photophone never achieved commercial success, although it worked rather well. Pleas