Fundamentals of Optical Communications - · PDF fileOptical Communication Systems 5. Outlook....

University of Applied Science

Hochschule Wismar

Departement of Electrical Eng. and Computer Science

Slide 1

Referent:Prof. Dr.-Eng. habilitasSteffen [email protected]

Fundamentals of

Optical Communications

Hochschule WismarFolie 2 Thema: Fundamentals of Optical Communications

Table of Contents

1. Basics of Optical Fibers

2. Dispersion

3. Optical Amplifiers / Pulse Reshaping

4. Optical Communication Systems

5. Outlook


Why Optical Fibres ...

Multi-utilization results in high efficiency ! Pinciple

Low Signal Attenuation

High Bandwidth

No EMI

Proof against Short-circuiting, Earthing and Fire

Data Security

Components with low Weight and Volume

Thema: Fundamentals of Optical Communications

Fiber Structure and Light Guiding Mechanism

ncladding = 1.48

ncore = 1.5

Step Index (SI) Fiber

r

n 125µm



ncladding = 1.48

ncore = 1.5

Step Index (SI) Fiber

• high dispersion > 100 ns/km

• attenuation ca. 1...15 dB/km


ncladding = 1.48

ncore = 1.5

Gradient Index (GI) Fiber

r

n



ncladding = 1.48

ncore = 1.5

Gradient Index (GI) Fiber

• low dispersion > 2 ns/km


• attenuation ca. 1...3 dB/km

V1=c/1.5

V2=c/1.48


ncladding = 1.48

ncore = 1.5

Single Mode (SM) Fiber

10µm

• almost no dispersion > 18ps/nm km


• attenuation ca. 0.2 dB/km


Fiber attenuation and optical windows

LS C

1.475 1.625[µm]

• WDM

• DWDM

1

dB/km

1.1 1.3 1.5 1.7µm

1.25 1.65[µm]

50 000GHz


Table of Contents


2. Dispersion



5. Outlook


Dispersion:

due to:

• „path differences“

• spectrum of light source

modal dispersion(intermodal dispersion)

chromatic dispersion(intramodal dispersion)

material dispersion waveguide dispersion

polarisation mode dispersion (PMD)


Modal Dispersion:

cn

NAC SIdalmo

1

2

,34 cn

NAC GIdalmo 3

1

4

,380

2

2

2

1 nnNAwith


Material Dispersion:


Waveguide Dispersion:

• can be neglected in multimode fibers

• caused by the different extension of LP01 into the cladding b( )leading to a wavelength dependent effective refractive index:

50

-50

1.0 1.61.4

nm kmps

[mm]

DMat

DWG

DChrom


Fiber dispersion of DSF

50

-50

1.0 1.61.4

nm kmps

m

DMat

DWG

Chromatic dispersion :

Dispersion ofa Dispersion Shifted Fiber (DSF)

DChrom


Fibers for dispersion compensation

Chromatic dispersion :

DChrom

50

-50

1.0 1.61.4

nm kmps

m

negative slope!


Table of Contents


2. Dispersion



5. Outlook


Erbium Doped Fiber Amplifier (EDFA)

isolator

pump laser

coupler

10 - 50mErbium doped fiber

30db

Popt=ca.17dBm


Optical pulse reshaping

ca. 10km

fiber with negative

dispersion slope

ca.120km ca.120km

SMF SMF


Table of Contents


2. Dispersion



5. Outlook


How does it work ?

Point-to-point:

OC1OC3STS1

MUX

O / E

OC1OC3STS1

DMUX

E / O

OC1OC3STS1

MUX

E / O

OC1OC3STS1

DMUX

O / E


How does it work ?

Point-to-point:

ATM/Ethernet/SDH line board


How does it work ?

MUX, but still point-to-point:

OC1OC3STS1

DMUX

E/O

OC1OC3STS1

MUX

E/O

OC12/1OC12/2OC12/3OC12/4

OC12/1OC12/2OC12/3OC12/4

(active)DWDMMUX

3 Tbps via 50km (2/1999)10.9 Tbps via 117km (9/2001)


How does it work ?

MUX, but still point-to-point:

Wave Line EL2: 32channels, 200GHz spacing


Table of Contents


2. Dispersion



5. Outlook


MUX-Generations

OFDM=> CWDM

OSDM

OFDM=> DWDM

FDM

SDMTDM

OTDM

space

freq

uen

cy


University of Technology, Business and Design

Hochschule Wismar

Referent:Prof. Dr. Steffen [email protected]

Thank you for listening to

‚Fundamentals of

Optical Communications‘


Departement of Electrical Eng. and Computer Science

Fundamentals of Optical Communications - · PDF fileOptical Communication Systems 5. Outlook....

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