《光通信技术》课件：Lecture_导论.pptVIP

Department of Optical Engineering, ZJUFiber-Optic Communications Technology Historical PerspectiveSmoke 1500Semaphore device 1500-1800Mechanic coding 1792 Claude ChappeDepartment of Optical Engineering, ZJU Optoelectronic Technology in Our Life EverydayDepartment of Optical Engineering, ZJU IntroductionWhy go digital? Advantage: less misinterpretationDisadvantage: requires more channel capacityMajor demandHigher capacityLower costDepartment of Optical Engineering, ZJU Shannon-Hartley theoremCapacity v.s. bandwidth (1948)Capacity (bits/sec)=BW(Hz)xlog2(1+SNR)Channel bandwidth v.s. Carrier-signal freq Channel bandwidth (Hz) ? 0.1XCarrier-signal freq. (Hz)Department of Optical Engineering, ZJU From copper wire to optical fiberCarrier-signal freq. limit:Copper wire 1MHzCoaxial cable 100 MHzRadio freq. 500KHz to 100 MHzMicrowave: 100 GHzLight: 100-1000THz!Department of Optical Engineering, ZJU Department of Optical Engineering, 2008 Capacity of Commercial Lightwave Systems Doubled Annually World record capacity 2012World Record in data transmission over a single fiber1 Petabit per second fiber transmission over 50 kilometers has been achieved in collaboration between Nippon Telegraph and Telephone Corporation, Fujikura Ltd., Hokkaido University, Japan, and DTU Fotonik’s High-Speed Optical Communications Group (HSOC). This technology makes it possible to send 5000 HDTV videos per second over a single fiber! Department of Optical Engineering, 2008 Enabling Technologies for Optic Comm.Three major developments are responsible for rejuvenation of optics its application in modern technology: 1- Invention of Laser 2- Fabrication of low-loss optical Fiber 3- Development of Semiconductor Optical Device As a result, new disciplines have emerged new terms describing them have come into use, such as: - Electro-Optics: is generally reserved for optical devices in which electrical effects play a role, such a