1 Stephen SchultzEE466 Fall Introduction

2 Stephen SchultzEE466 Fall 2007 Communication Links

3 Stephen SchultzEE466 Fall 2007 Undersea Optical Fiber Backbones

4 Stephen SchultzEE466 Fall 2007 Fiber Data Rate

5 Stephen SchultzEE466 Fall 2007 Fiber Capacity

6 Stephen SchultzEE466 Fall 2007 Multiplexing

7 Stephen SchultzEE466 Fall 2007 TDM Standards Standards developed for optical fiber communications rates –Synchronous Optical NETwork (SONET) –Synchronous Digital Hierarchy (SDH) SONETSDHB (Mb/s)Channels OC OC-3STM ,016 OC-12STM ,064 OC-48STM-162, ,256 OC-192STM-649, ,024 OC-768STM-25639, ,096

8 Stephen SchultzEE466 Fall 2007 Optical Signal Optical signals are typically sent using on-off keying (OOK) –Power received: 1 –No power: 0 Two primary formats –Nonreturn to zero (NRZ) –Return to zero (RZ)

9 Stephen SchultzEE466 Fall 2007 Basic Optical Communication Link Electrical signal transferred to another location –Electrical-to-Optical (E-O) conversion Modulated laser –Signal transmission Optical fiber –Optical-to-Electrical (O-E) conversion Detector

10 Stephen SchultzEE466 Fall 2007 Signal Transmission Signal is attenuated as it propagates through the fiber –Decrease in signal amplitude –Reduction in signal-to-noise ratio (SNR) Pulse is spread in time –Called signal dispersion –Causes inter-symbol interference (ISI)

11 Stephen SchultzEE466 Fall 2007 Additional Components External modulator –Better signal—lower signal dispersion Optical amplifier –Amplifies signal to overcome attenuation

12 Stephen SchultzEE466 Fall 2007 Topics to be Covered Fibers –Attenuation –Dispersion Sources Detectors System performance