Crosstalk And Dispersion in optical networks

Presented By : Kuldeep singh

ICE2012015

Topics covered

• Crosstalk – Intrachannel crosstalk

– Interchannel crosstalk

• Bidirectional system• Crosstalk reduction

– Spatial dilation

– Wavelength dilation

• Dispertion – Intermodal dispersion

– Polarization-mode dispersion

– Chromatic dispersion

• Chromatic dispersion limits (NRZ/RZ modulation)• Dispersion compensation

– Dispersion compensation fibers

– Chirp fiber Bragg gratings2

3

Crosstalk in WDM Switch

R1, G1, B1

R2, G2, B2

R3, G3, B3 R1, G2+G1, B3

• Imperfect separation of R1 and G1 at input demux means G1 mixes with G2 on output

4

Intrachannel crosstalk

Interchannel crosstalk

5

Worst-case received power

For intrachannel :

For interchannel :

Power penalty

6

Bidirectional system

7

Crosstalk Reduction

8

Dispersion

• Intermodal dispersion : only in multimode fibers• Polarization-mode dispersion : due to fiber core is not perfectly circular (big issue for very high speed system operating at 10Gbps bit rates and beyond)

Cromatic dispersion : arises because different frequency components of pulse travel with different group velocity.

Chromatic dispersion limits:

9

Dispersion compensation

10

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Thank you