SEEFIRE Optical Amplifiers and Line Spans www seefire

SEEFIRE Optical Amplifiers and Line Spans www. seefire. org Josef Vojtěch CESNET Czech Republic josef. vojtech(at)cesnet. cz www. ces. net The SEEFIRE project is co-funded by the European Commission under the FP 6 IST contract no. 15817

Overview Optical Amplifiers in General Optical Fibre Amplifiers, EDFAs Ramans SOAs Amplifiers for (D)WDM Line Spans Single Span (NIL) Multi Span SEEFIRE Technical Workshop – Sofia, Bulgaria, 14 -15 July 2005 2

Optical Amplifiers in General Ideal Optical Amplifier (OA) High gain, polarization independent Large bandwidth High output power Adds no noise Basic types of OA (according principle) Optical fibre amplifiers Raman OA Semiconductor OA (SOA) SEEFIRE Technical Workshop – Sofia, Bulgaria, 14 -15 July 2005 3

Optical Fibre Amplifiers Active environment – special fibre doped with one or more rare earth element (Er, Nd, Pr, Tm, …or combination Er/Yb, Tm/Yb, . . ) PDFA Pr doped, suitable for (1280 -1340 nm) G>30 d. B, Pout >16 d. Bm, NF <7 d. B TDFA Tm doped, suitable for (1440 -1520 nm) G>30 d. B, Pout >20 d. Bm, NF <7 d. B SEEFIRE Technical Workshop – Sofia, Bulgaria, 14 -15 July 2005 4

Erbium-Doped Fiber Amplifiers Most widespread in telecommunications Suitable for C band (lowest fiber attenuation) common silica glass Advantages Operating range in 1520 -1610 nm G>45 d. B, Pout >37 d. Bm, NF in <3. 5, 7>d. B Multi-channel crosstalk very low Polarization independent Disadvantages Not small devices, cannot be integrated with other semiconductors Gain spectrum not inherently flat SEEFIRE Technical Workshop – Sofia, Bulgaria, 14 -15 July 2005 5

Raman Amplifiers Based on simulated Raman scattering, active environment – common (non- doped) fiber G in <10, 15> d. B, Pout >30 d. Bm, NF < 1 d. B Advantages Usable in 1250 -1650 nm regions Bandwith can be tailored (1 pump 35 nm, more pump up to 90 nm) Lower NF than EDFA High process efficiency in DCF (loss -> gain) component Disadvantages Higher interchannel crosstalk than EDFA High pump powers (safety issues) SEEFIRE Technical Workshop – Sofia, Bulgaria, 14 -15 July 2005 6

Semiconductor Optical Amplifiers Based on conventional laser principle, active environment – waveguide region sandwiched between n and p regions G>25 d. B, Pout >15 d. Bm, NF in <7, 10>d. B Advantages Usable in 1310 1550 nm regions Wide band (40 -80 nm) Small compact semiconductors, easy to integrate Disadvantages Higher NF than EDFA Higher interchannel crosstalk than EDFA Polarization sensitive SEEFIRE Technical Workshop – Sofia, Bulgaria, 14 -15 July 2005 7

Spectral usability of Amplifiers O S C L SEEFIRE Technical Workshop – Sofia, Bulgaria, 14 -15 July 2005 8

Amplifiers for (D)WDM I EDFA – needs gain flattening Glass composition (F, Te glass host) Single stage EDFA, silica host: bandwidth 15 nm Single stage EDFA, fluoride host: bandwidth 25 nm Equalizers Two stage, silica or fluoride host, no gain flattening: 30 nm Two stage, silica host, gain flattening: 50 nm Two stage, tellurite host, gain flattening: 80 nm Hybrid OA Multi-arm - two band operation, silica host: 85 nm SEEFIRE Technical Workshop – Sofia, Bulgaria, 14 -15 July 2005 9

Amplifiers for (D)WDM II Hybrid EDFA/Raman Bandwidth can be tailored ~80 nm Lower NF than EDFA separate Signal power in periodically amplified system. Comparison between original (EDFA system) and hybrid system OSNR improvement SEEFIRE Technical Workshop – Sofia, Bulgaria, 14 -15 July 2005 10

Line Spans Main path length limitations Losses Optical power budget of a path (System margin) = (Tx output power) – (Rx sensitivity) – (ƩLoses) Chromatic dispersion Polarization-mode dispersion (>=10 Gb/s) SEEFIRE Technical Workshop – Sofia, Bulgaria, 14 -15 July 2005 11

Line Spans Other limitations OSNR (esp. in amplifier cascades) Crosstalk Fiber nonlinearities Stimulated Raman and Brillouin scattering Four-wave mixing, Self-phase mudulation, cross-phase modulation SEEFIRE Technical Workshop – Sofia, Bulgaria, 14 -15 July 2005 12

Single span Loss limitations especially CD - needn´t be fully compensated No accumulation of noise and nonlinear effect Results - vendor 1 Results - vendor 2 80 channels @10 Gb/s - 46 d. B 20 channels @ 10 Gb/s - 57 d. B 20 channels @10 Gb/s - 60 d. B (66 d. B) 1 channels @2. 5 Gb/s - 68 d. B 1 channel @10 Gb/s - 63 d. B (75 d. B) CESNET results 1 channel @10 Gb/s - 65 d. B SEEFIRE Technical Workshop – Sofia, Bulgaria, 14 -15 July 2005 13

Multiple span Noise and nonlinear effect accumulation Typical span 20 or 25 d. B Given by non amplified OSC channel (1510 nm, 1625 nm) Example of system performance 80 channels@10 Gb/s 30*20 d. B or 16*25 d. B, 25*25 d. B with Raman ampliffication However exist 35 d. B span systems OSC is amplified (1550 nm) SEEFIRE Technical Workshop – Sofia, Bulgaria, 14 -15 July 2005 14

Bibliography Ramaswami R. , Sivarijan K. N. , “Optical Networks“, 2 nd edition, 2002. Agrawal G. P. , “Fiber-Optic Comminications Systems”, 2002. Islam M. N. , ”Raman Amplifiers for Tellecomunication 1, 2”, 2004. Becker P. C. , Olsson N. A. , Simpson J. R. , “Erbium-Doped Fiber Amplifiers”, 1999 SEEFIRE Technical Workshop – Sofia, Bulgaria, 14 -15 July 2005 15

Amplifier Examples EDFA Raman SOA SEEFIRE Technical Workshop – Sofia, Bulgaria, 14 -15 July 2005 16

Thank you for your attention! Questions? SEEFIRE Technical Workshop – Sofia, Bulgaria, 14 -15 July 2005 17