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We propose to use a genetic algorithm to determine the physical parameters of Bragg gratings from their reflection spectra for both design purposes and fiber sensor applications. A real-coded genetic algorithm is used for inversion purposes, along with an F-matrix formalism for synthesis of uniform, chirped, and apodized gratings. An example of bandpass filter design is also studied. The method is easily applicable and shows promising results.

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This work describes straightforward access to a large collection of thietane derivatives through an innovative two-step domino photochemical reaction involving a Norrish type II fragmentation and a thia-Paternò–Büchi reaction. Starting from stable phenacyl sulfides, unprecedented thiocarbonyl intermediates were generated in situ and reacted with diverse electron-deficient alkene partners to form a thietane core. The rules governing the regio- and diastereoselectivity of this [2+2] photocycloaddition have been rationalized and fully controlled for many substrates.