1. Report on
Dispersion management of optical fiber communication

2. Presented by
Titas Kumer Sarker : 510
BSc in Electrical and Electronic Engineering
International Business Administration and
Information System University
Submitted To
Md Hasan Rahman
Lecturer
Department of Electrical and Electronic Engineering
International Business Administration and Information
System University

3. Overview of optical fiber communication

4. Basic concept of optical Fiber
Core
Carries the signal
Cladding
Glass or plastic with a lower index
of refraction than the core
Buffer
Protects the fiber from damage
and moisture
Jacket
Holds one or more fibers in a
cable
Optical fiber transmits light pulses can be used for analog or digital transmission
voice, computer data, video, etc. An optical fiber have following those :

5. Optical TransmitterOptical Transmitter
Definition: a device that converts
electrical signal into optical signal
Lasers
Fabry-Perot Lasers (FP)
Distributed Feedback Lasers (DFB)
Vertical Cavity Surface Emitting Lasers
(VCSEL)
ASE fiber laser
Light Emitting Diodes (LED)
Surface-Emitting LED (SLED)
Edge-emitting LED (EELED)

6. OpticalOptical ReceiverReceiver
Definition: convert optical signal into electrical signal
Types:
p-i-n photo detector: photon-electron converter
Avalance photo detector (APD): more sensitive for high speed
systems
Photo detector parameters:
Responsively: the amount of current produced per unit of
input optical power
Wavelength bandwidth: the bandwidth the PD is sensitive to.
Damage threshold: the maximum optical power the PD can
take before damage

7. Advantages of Optical Fiber
Thinner
Less Expensive
Higher Carrying Capacity
Less Signal Degradation& Digital Signals
Light Signals
Non-Flammable
Light Weight

8. Attenuation
Modern fiber material is very pure, but there is still some attenuation
The wavelengths used are chosen to avoid absorption bands
850 nm, 1300 nm, and 1550 nm
Plastic fiber uses 660 nm LEDs
• Image from iec.org (Link Ch 2n)

9. Dispersion
Dispersion is the spreading out of a light
pulse as it travels through the fiber
Three types:
Material Dispersion
Webguide Dispersion
Polarization Mode Dispersion (PMD)

10. Material Dispersion
Material dispersion comes from a frequency dependent response of a material of waves.

11. Waveguide dispersion
For fibers, waveguide dispersion is in the same order of material
dispersion. The pulse spread can be well approximated as:
2
2
2 )(
)(
dV
Vbd
V
c
Ln
DL
d
d
wg
wg
wg
λ
σ
λσσ
λ
τ
σ λ
λλ
∆
==≈ )(λwgD

12. Polarization Mode dispersion
Core
z
n1x
// x
n1y
// y
Ey
Ex
Ex
Ey
E
∆τ = Pulse spread
Input light pulse
Output light pulse
t
t
∆τ
Intensity
Suppose that the core refractive index has different values along two orthogonal
directions corresponding to electric field oscillation direction (polarizations). We can
take x and y axes along these directions. An input light will travel along the fiber with Ex
and Ey polarizations having different group velocities and hence arrive at the output at
different times
© 1999 S.O. Kasap, Optoelectronics (Prentice Hall)

13. Total Dispersion, zero Dispersion
Fact 1) Minimum distortion at wavelength about 1300 nm for single mode silica fiber.
Fact 2) Minimum attenuation is at 1550 nm for sinlge mode silica fiber.
Strategy: shifting the zero-dispersion to longer wavelength for minimum attenuation and dispersion.

14. Differences in speed cause spreading
or dispersion of wave packets

15. Difference between Gaussian theorem
and Super Gaussian Theorem
Gaussian Pulse
(For 5 Gbps)
Super Gausian
Pulse ( For 5 Gbps)

16. Difference between Gaussian theorem
and Super Gaussian Theorem
Gaussian Pulse
(For 10 Gbps)
Super Gausian
Pulse(For 10 Gbps)

17. Differences between Gaussian theorem
and Super Gaussian Theorem
Gaussian Pulse
(For 20 Gbps)
Super Gausian
Pulse(For 20 Gbps)

18. Differences between Gaussian theorem
and Super Gaussian Theorem
Gaussian Pulse
(For 30 Gbps)
Super Gausian
Pulse(For 30 Gbps)

19. Differences between Gaussian theorem
and Super Gaussian Theorem
Gaussian Pulse
(For 40 Gbps)
Super Gausian
Pulse(For 40 Gbps)

20. Conclusion
This concludes our study of Fiber Optics. We have looked at how
they work and how they are made. We have examined the
transmitter and receiver of fibers, and how fibers are work. Here
briefly explained attenuation and dispersion optical fiber. I have also
explained Gaussian Pulse and Super Gaussian Pulses. I got a sound
knowledge after that research if we use Super Gaussian Pulses
dispersion will be reduced. So that we should use Super Gaussian
pulse. Although this presentation does not cover all the aspects of
optical fiber work it will have equipped you knowledge and skills
essential to the fiber optic industry.

21. Thank you for your kind patience.
Have a nice time for all.....
How can I serve you?
Email : titasce@gmail.com.com
Skype : titasce