Design and fabrication of superimposed fiber Bragg gratings: towards the optimality

Mikhail Popov; Fredrik Carlsson; Pierre-Yves Fonjallaz

doi:10.1117/12.468561

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15 April 2003 Design and fabrication of superimposed fibre Bragg gratings: towards the optimality

Mikhail Popov, Fredrik Carlsson, Pierre-Yves Fonjallaz

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Proceedings Volume 4943, Fiber-based Component Fabrication, Testing, and Connectorization; (2003) https://doi.org/10.1117/12.468561
Event: Photonics Fabrication Europe, 2002, Bruges, Belgium

Abstract

Design and fabrication of superimposed fibre Bragg gratings are considered. Firstly, an accurate numerical model for computing the reflection and transmission spectra of the superimposed gratings is presented. The model employs the transfer matrix method and takes into account the photosensitivity profile of the fibre, which is understood as the dependence of the refractive index change versus UV light exposure dose. It is shown that the model accurately reproduces the impact of saturation of the photosensitivity profile on the reflection and transmission spectra of the superimposed grating. Secondly, by varying the initial phase of each elementary grating comprising the superimposed one, the latter is optimised such that the total maximum refractive index change required is minimised. The optimisation is carried out by means of the genetic algorithm, a global optimisation technique. A method for an almost optimal use of the fibre photosensitivity is proposed. The method overcomes the problems related to the non-infinitesimal length of the interferometric pattern in the grating writing setup. A successful fabrication of optimised 8- and 16-channel filters for a 2.5 Gb/s DWDM system with 50 GHz channel separation is reported. It is shown that the optimised superimposed gratings have a smaller insertion loss than similar non-optimised ones.

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Mikhail Popov, Fredrik Carlsson, and Pierre-Yves Fonjallaz "Design and fabrication of superimposed fibre Bragg gratings: towards the optimality", Proc. SPIE 4943, Fiber-based Component Fabrication, Testing, and Connectorization, (15 April 2003); https://doi.org/10.1117/12.468561

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