Telecommunications
DESIGN OF A CHIRPED FIBER BRAGG GRATING FOR USE IN WIDEBAND DISPERSION COMPENSATION
İsa Navruz e-mail: inavruz@eng.ankara.edu.tr
Ahmet Altuncu e-mail: altuncu@mail.dumlupinar.edu.tr
Key words: Fiber Bragg grating , dispersion compensation, apodization ABSTRACT A wideband chirped fiber Bragg grating (FBG) dispersion compensator operating in C band is designed theoretically by numerically solving the coupled mode equations. The power reflectivity spectrum and dispersion characteristics of the chirped fiber Bragg gratings are analysed. In order to achieve wideband dispersion compensation with a low insertion loss, grating length, average refractive index change, apodization profile and chirp parameter of the grating should be precisely optimized. The chirped FBG designs achieved in this study have resulted in a negative dispersion of 4.95 ps/nm for a grating length of L = 10 mm and a negative dispersion of 9.76 ps/nm for a grating length of L = 20 mm with 16 nm bandwidth at around 1550 nm. recognized as a perfect alternative do DCF. The most significant advantages of chirped FBGs are low insertion loss, nonlinear effects and cost. The idea of dispersion compensation using chirped fiber gratings was firstly proposed by Qulette [4] and later demonstrated experimentally by Williams et.al. [5]. A fiber Bragg grating is a reflective device composed of an optical fiber that contains a modulation of its core refractive index over a certain length. The grating reflects light propagating through the fiber when its wavelength corresponds to the modulation periodicity. In a chirped FBG, the periodicity of the induced index modulation varies along the grating’s length. As the grating period varies along the axis, the different wavelengths are reflected by different portions of the grating and accordingly are delayed by different amounts of time. The net effect is a compression of the input pulse that can be tailored to compensate for the chromatic dispersion accumulated
İsa Navruz e-mail: inavruz@eng.ankara.edu.tr
Ahmet Altuncu e-mail: altuncu@mail.dumlupinar.edu.tr
Key words: Fiber Bragg grating , dispersion compensation, apodization ABSTRACT A wideband chirped fiber Bragg grating (FBG) dispersion compensator operating in C band is designed theoretically by numerically solving the coupled mode equations. The power reflectivity spectrum and dispersion characteristics of the chirped fiber Bragg gratings are analysed. In order to achieve wideband dispersion compensation with a low insertion loss, grating length, average refractive index change, apodization profile and chirp parameter of the grating should be precisely optimized. The chirped FBG designs achieved in this study have resulted in a negative dispersion of 4.95 ps/nm for a grating length of L = 10 mm and a negative dispersion of 9.76 ps/nm for a grating length of L = 20 mm with 16 nm bandwidth at around 1550 nm. recognized as a perfect alternative do DCF. The most significant advantages of chirped FBGs are low insertion loss, nonlinear effects and cost. The idea of dispersion compensation using chirped fiber gratings was firstly proposed by Qulette [4] and later demonstrated experimentally by Williams et.al. [5]. A fiber Bragg grating is a reflective device composed of an optical fiber that contains a modulation of its core refractive index over a certain length. The grating reflects light propagating through the fiber when its wavelength corresponds to the modulation periodicity. In a chirped FBG, the periodicity of the induced index modulation varies along the grating’s length. As the grating period varies along the axis, the different wavelengths are reflected by different portions of the grating and accordingly are delayed by different amounts of time. The net effect is a compression of the input pulse that can be tailored to compensate for the chromatic dispersion accumulated