N-GEN Communications Web-based Seminars ©NGCS

Seminar - An Overview of Communications Technologies

Module 5 - SONET, WDM, DWDM and B-ISDN Technologies                                                             Slide 17 of 76 _________________                                                                                  __________

                                        Optical Amplifiers

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Optical amplifiers are different than electro-optical amplifiers. Optical amplifiers are not signal regenerators performing reshape, retime and retransmit functions. Optical amplifiers amplify all the wavelengths. Erbium, a rare-earth material, is used to dope fiber to create signal amplification. A weak signal enters the erbium-doped fiber, into which light at 980 mm or 1480 nm is injected by using a pump laser. The injected light stimulates the erbium atoms and releases a stronger signal at 1550 nm.