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

conventional SOA GC-SOA (Gain-Clamped SOA) LOA (Linear Optical Amplifier) (SOA) 

Fiber Optical amplifiers

(FOA)

Rare earth-Doped Fiber Amplifiers

Erbium-Doped Fiber Amplifiers (EDFA)

Thulium-Doped Fiber Amplifiers (TDFA)

: C, L-Band

: 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 (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

Tellurite EDF 1 2 IN OUT WDM coupler 4 m 1.48

m

m pump LD 10 m WDM coupler 1.48

m

m pump LD 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 amplifiers 1440 1460 1480 1500 1520 1540 1560 EDFA ~47 nm 1580 1600 1620 1640 1660 nm EDFA 52 nm Fluoride EDFA 62 nm Tellurite EDFA 76 nm] TDFA 37 nm TDFA 35 nm Raman + 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 1440 1460 1480 1500 1520 1540 1560 1580 1600 1620 1640 1660 nm E-Band S-Band C-Band L-Band U-Band

Fiber Raman Amplifiers

Discrete gain R a m a n fiber I 5.0 km Distributed gain DSF 50 km MZ Ga in EQ.

IN WDM coupler Divider R a m a n fiber II 8.3 km 1.545

m

m pump LD I II 5.0 km IV 5.0 km 1.415

m

m pump LD WDM coupler WDM coupler 1.475

m

m pump LD 1.545

m

m pump LD 1.465

1.495

1.510

m

m

m

m

m

m pump LD Combiner 1.545

m

m pump LD OUT

 

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

:

1.3~1.7 um

wavelength) (tunable by pump

132 nm record gain bandwidth in double band configuration

been achieved [H. Masuda et al., ECOC’99].

- Combination of

Distributed Raman amplifiers (DRA) and discrete Raman

has - 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 Cisco 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,



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!