Inside the optical networks… A closer look to the amplifiers Part II Hop Ton That

Traditional Configuration of WDM Systems

Optical amplifier type 2 major classes: Semiconductor Optical Amplifiers (SOA) conventional SOA GC-SOA (Gain-Clamped SOA) LOA (Linear Optical Amplifier) Fiber Optical amplifiers (FOA) Rare earth-Doped Fiber Amplifiers Erbium-Doped Fiber Amplifiers (EDFA) : C, L-Band Thulium-Doped Fiber Amplifiers (TDFA) : S-Band Praseodymium-Doped Fiber Amplifiers (PDFA) : O-Band

Other optical amplifier type Not based on stimulated emission but on nonlinear effects Fiber Raman Amplifiers Discrete Raman Amplifiers Distributed Raman Amplifiers (DRA) Hybrid EDFA/Raman Amplifier

EDFA: Pumping mechanism

EDFA Configuration Co-propagating pump= lower noise but lower output power Counter-propagating pump= higher output power but higher noise

EDFA Noise

Output vs wavelength Amplification between 1.53 and 1.56 um.

Rare earth (Er, Tm, Pr) -Doped Fiber Amplifiers Gain band: Er (C, L-Band), Tm (S-Band), Pr (O-Band) 76 nm ( nm) record gain bandwidth in single band configuration [M. Yamada et al.,OFC’98PD]. - Flat gain: 21 dB, Noise figure: 7 dB - Gain equalizer: two MZ filters with FSR of 32 and 120 nm

Stimulated Scattering is transferring energy from the incident wave to another, scattered wave at lower frequency (longer wavelength) with the small energy difference being release as phonons. The incident wave can be seen as a pump wave. (Scattered waves are called Stokes waves)

Stimulated Scattering 2 types:- Stimulated Raman Scattering (SRS) - Stimulated Brillouin Scattering (SBS) In WDM systems, SBS has almost no effect

Distributed Raman Amplifier (DRA) DRA is based on Raman Scattering. A large pump is co- launched at a lower wavelength than the signal to be amplified

Typical Raman Gain Curve versus Wavelength

DFA vs DRA

Hybrid EDF/Raman Amplifier

Gain bandwidth of optical amplifiers

Fiber Raman Amplifiers Gain band: 1.3~1.7 um (tunable by pump wavelength) 132 nm record gain bandwidth in double band configuration has been achieved [H. Masuda et al., ECOC’99]. - Combination of Distributed Raman amplifiers (DRA) and discrete Raman - Two-gain-band Raman amplifier

Companies working in the optical transport network technology field. Europe Nokia, Ericsson Telecom, Ericsson Comp., Telia, Sonera, Teledanmark, Lucent Nederlands, BT, Marconi, Nortel Networks(Euro), Siemens, Swisscom, France Telecom, ……Italtel, Telecom Italia, Alcatel SEL, Alcatel Italy, Pirelli, Telecom Italia, CSELT, Ukraine, Marconi North America AT&T, Corning, Ciena, EXFO, Elisa, Fujitsu Networks(US), JDS, Lucent(US), Hitachi Telecom(US), Motorola, NEC(US), Nortel, Networks(US, Canada), MCI Worldcom, Sprint, Telcordia, Tycom, Ciena, Cisco Asia China Telecom, China Unicom, CLPAJ, Corning Int. DDI, ETRI, Fujitsu, Hitachi, Huawei Technol., Japan Telecom, Korea Telecom, KDDI, Mitsubishi, NEC, NTT, Oki, Shanghai Bell, Sumitomo, Sumsung, Toshiba

Bibliography Télécommunications par fibres optiques: Historical part flash animations Raman Amplification Design in WDM Systems (IEC Tutorial) Book: Fiber-Optic Communications Technology, course book.

Questions

The end! Thank you for your patience!