الفهرس 
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Abstract
In this thesis, erbium-doped fiber amplifier (EDFA) gain flatness using cascaded fiber Bragg grating (FBG) is studied at C-band (1530-1560 nm). The gain characteristics in reference to the wavelength, EDFA length, erbium ion density, and erbium radius are investigated. Three host materials are used: conventional silica, fluoride, and aluminogermanosilica. The absorption and emission cross-section areas of the host materials are obtained by Gaussian fitting parameters using Matlab. A comparison of the gain flatness of three host materials using different number of FBGs is carried out. The convectional silica exhibits a high gain of 38.5 dB before flattening with an in-band gain of 6.5 dB. After flattening, the gain is dropped to 29 dB with a relative gain of 1.3% when the number of FBGs used is reduced to 10. The bandwidth of 28.42 nm realized with 20 and 10 FBGs configuration while the 30 FBGs configuration achieves a slightly lower value of 25 nm. The fluoride as a host material depicts a lower gain after flattening of 12 dB, minimum relative gain difference of 10% with 30 FBGs and bandwidth of 28.42 nm. The aluminogermanosilicate depicts the highest gain of 30 dB when flattened with a relative gain difference of 1% at 30 FBGs configuration. A bandwidth of 28 nm is achieved.