Dispersion compensation by using chirped fiber BRAGG

Dissertant

Abd al-Rahman, Ali

University

University of Technology

Faculty

-

Department

Department of Electrical Engineering

University Country

Iraq

Degree

Master

Degree Date

2004

English Abstract

Fiber Bragg gratings have emerged as important components in a variety of light wave applications, such as, dispersion compensation, with is the prime importance of this work.

Direct numerical integration methods are used to characterize and design reflection spectrum of fiber grating, where 4 -order Runge-Kutta algorithm is used to solve FBGS Riccati-equation, In addition, two other numerical methods are used to design FBGS.

For certain values of refractive index difference, FBGS display an exponentially decreasing behavior of FBGS length with reflection bandwidth while displaying an exponential increase between FBG length and maximum power reflectivity.

Various iodization profiles (sine, sin1, sine, gauss and tan) are t-applied to the refractive index along uniform FBGS length.

As expected, iodization functions result in removal of unwanted side lobe peaks and smoothing time delay ripple response.

Among various iodization profiles, Gaussian anodized function gives the best performance, as it completely removes these parasitic side lobe peaks.

It is shown that linearly chirped FBGS provide the mean for dispersion compensation, but they are far from satisfactory for use in high performance dispersion compensation.

This is attributed to reflection and time-delay characteristics suffering from relatively large ripples vary with grating maximum reflectivity.

Various suggested iodization profiles are applied to non-uniform gratings to investigate their effect on the grating characteristics.

It is found that these iodization functions possess greatly flattened spectrum and linearized time delay response.

Also, the dispersion characteristics of anodized linearly-chirped fiber grating have been studied systematically.

It is shown that the hyperbolic target profile (that) results in overall superior performance, as it provides highly linearized time-delay characteristic with minimum reduction in linear dispersion.

This results in compensated fiber links of maximum length and minimum transmission penalty.

It is shown that in order to compensate for the linear dispersion of 100km of standard single mode fiber (SSMF) (D = 17 ps / nm.

km) over certain bandwidth (in nm) the required grating length is (22.17 cm / nm) when that iodization profile is used.

The required length is (18 : 86 cm / nm) in the unapodized case and increases to (33.6 cm / nm) when sine iodization profile is utilized.

Computer simulation is performed to verify the use of that anodized CFBG as dispersion compensation.

The input Gaussian pulse has (0.36 ps) duration is compressed to (0.1 ps) output reflected pulse.

Finally five channel dispersion compensation that anodized CFBG are designed using parallel-connected chirped gratings.

The simulation programs are performed using MATLAB 6.1 software running on Pentium 4 (1.7 GHZ) computer.

Main Subjects

Physics

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-305497