Ee 230 optical fiber communication lecture 4 l.jpg
Sponsored Links
This presentation is the property of its rightful owner.
1 / 17

EE 230: Optical Fiber Communication Lecture 4 PowerPoint PPT Presentation


  • 194 Views
  • Uploaded on
  • Presentation posted in: General

EE 230: Optical Fiber Communication Lecture 4. Fiber Dispersion. From the movie Warriors of the Net. Types of Dispersion. Modal dispersion: different modes propagate at different group velocities Material dispersion: the index of refraction of the medium changes with wavelength

Download Presentation

EE 230: Optical Fiber Communication Lecture 4

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


EE 230: Optical Fiber Communication Lecture 4

Fiber Dispersion

From the movie

Warriors of the Net


Types of Dispersion

  • Modal dispersion: different modes propagate at different group velocities

  • Material dispersion: the index of refraction of the medium changes with wavelength

  • Waveguide dispersion: index change across waveguide means that different wavelengths have different delays

  • Polarization mode dispersion: if waveguide is birefringent


Definitions

Group velocity

Group delay

Dispersion


Wave Packet Construction


Group and Phase Velocity


Transform Limited Frequency Spread

Pulse modulated Sine wave

Rectangular Pulse

Optics-Hecht & Zajac

Gaussian modulated Sine wave


Spectral properties of digitally modulated signals1

No spectral component at the clock frequency

For Non-Return to Zero Encoded Data


Pulse Propagation through Fibers

Response of a multi-mode fiber to a single

short pulse

Broadening of a short pulse after transmission

through different types of fibers

Fundamentals of Photonics - Saleh and Teich


Material Dispersion

Refractive Index of Pure Silica and its derivatives

Material Dispersion Parameter for pure silica

and germanium doped silica

Optical Fiber Communications-Keiser

Fiber Optic Communications-Palais


Zero Dispersion Slope

Fiber Optics Communication Technology-Mynbaev & Scheiner


Fiber Dispersion

Dispersion:The change in speed of propagation with wavelength

Pulse Degradation from Dispersion

Typical fiber Dispersion Curve

Ray optics View of the origin of waveguide dispersion


Polarization Mode Dispersion

Polarization Maintaining Fiber

Non-Polarization Maintaining Fiber

Random power transfer occurs between different polarization modes

as the pulse propagates, if the two modes have different propagation velocities

then the pulse will broaden


Representative Fiber Characteristics


Dispersion for various Fiber Types


Dispersion Shifted and Dispersion Flattened Fibers

Chromatic Dispersion Parameters of

a singlemode fiber

  • Waveguide Dispersion mechanism

    • As l Ý,Mode field diameter Ý

    • More of the mode travels in the cladding.

    • Cladding index is lower so pulse velocity Ý

    • resulting in dispersion ß

Fundamentals of Photonics - Saleh and Teich


Comparison of Dispersion Characteristics


Propagation of Gaussian Pulses

Input Pulse

Output Pulse

chirped and broadened

b2<0 for standard single mode silica fiber

and Ld ~ 1800 km at 2.5 Gb/s and ~115 km at 10 Gb/s

Upon further propagation

the pulse will continue to broaden

and acquire chirp.

Input Pulse

Already Positively

Chirped

After some distance

the chirp is removed

and the pulse assumes its

minimum possible width

Optical Networks a Practical Perspective-Ramaswami and Sivarajan


  • Login