Structured Chirped Fiber Bragg Gratings

• Published in: Journal of lightwave technology 2008-06, Vol.26 (12), p.1613-1625
• Main Authors: Pisco, M., Iadicicco, A., Campopiano, S., Cutolo, A., Cusano, A.
• Format: Article
• Language: English
• Subjects: Applied sciences; Bandwidth; Bragg gratings; Channels; Chirped fiber bragg grating; Circuit properties; Coding, codes; Defects; Devices; Diffraction gratings; Electric, optical and optoelectronic circuits; Electronics; Exact sciences and technology; Fiber gratings; Gratings (spectra); Information, signal and communications theory; Integrated optics. Optical fibers and wave guides; Laser tuning; Mathematical models; Microfluidics; microstructure devices; Optical and optoelectronic circuits; Optical devices; optical fiber devices; Optical filters; Optical sensors; optical transducers; Periodic structures; Photonic band gap; Signal and communications theory; Spectra; Studies; Telecommunications and information theory; Thinning
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2008.920597

In this paper, a theoretical and numerical analysis of novel in-fiber photonic devices based on a structured chirped fiber Bragg gratings (CFBGs) for sensing and communication applications is presented. The investigated structure consists in a CFBG with single or multiple defects obtained by a deep and localized stripping of the cladding layer along the grating structure. The thinning of the cladding layer, partial or total, changes the core propagation features and thus leads to a significant modification of the grating spectral features. The effect of the local thinning, properly exploited, basically consists in the formation of one or more passbands within the original grating bandwidth and in one or more stopbands out of the original grating bandwidth. In addition, due to spatial encoding of the Bragg wavelength in CFBGs, the spectral position of each channel exclusively depends on the features of its own defect in a well defined location along the grating. Thus, the spectral properties of each channel are not affected by additional defects located elsewhere along the grating structure, enabling the possibility to develop independent multichannel devices by exploiting a single grating element. The spectral behavior exhibited by the microstructured device has been here numerically analyzed in dependence on the thinned region parameters. In addition a simple theoretical model has been extracted in order to easily design the device according to the desired spectral features for specific applications.