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 SOAGC-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-BandPraseodymium-Doped Fiber Amplifiers (PDFA) : O-Band

Other optical amplifier type

Not based on stimulated emission but on nonlinear effects

Fiber Raman AmplifiersDiscrete Raman AmplifiersDistributed Raman Amplifiers (DRA)

Hybrid EDFA/Raman Amplifier

EDFA: Pumping mechanism

EDFA Configuration

Co-propagating pump= lower noise butlower output power

Counter-propagating pump= higher outputpower 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 (1532-1608 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

1.48 mpump LD

WDM coupler

1.48 mpump LD

WDM coupler

Tellurite EDF 1 2

4 m 10 m

IN OUT

MZ Gain EQ.

M. Yamada et al., OFC’98 PD, PD7, 1998

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 amplifiers1660 nm1640162016001580156015401520150014601440 1480

1660 nm1640162016001580156015401520150014601440 1480

Fluoride EDFA 62 nm

EDFA 52 nm

EDFA ~47 nm

Tellurite EDFA 76 nm]

TDFA 37 nm

TDFA 35 nmRaman + Fluoride EDFA 80 nm

Dist. Raman + Fluoride EDFA 83 nm

Raman + TDFA 53 nm

Raman 18 nm

Raman 40 nm

Raman 100 nm

Raman 132 nm

C-Band L-BandS-Band U-BandE-Band

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

1.475 mpump LD

W DM coupler

1 .465 m1.495 m1.510 mpum p LD

W DM coupler

R a m a n fiber II8.3 km

I I I5 .0 k m

IN

OUT

MZ Ga in EQ .

H. Masuda et al., ECOC’99, II-146, 1999

1.545 mpum p LD

IV5.0 km

1.545 mpum p LD

R a m a n fiber I5.0 km

1.545 mpum p LD

Com binerDivider

1 .415 mpum p LD

W DM coupler

DSF 50 km

Distributed gain

Discrete gain

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

www.google.com Télécommunications par fibres

optiques: Historical part www.unice.fr/dess_ntic: flash

animations Raman Amplification Design in

WDM Systems (IEC Tutorial) www.iec.org/online/tutorials/raman

Book: Fiber-Optic Communications Technology, course book.

Questions

The end!

Thank you for your patience!