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Transition of refractive index contrast in course of grating growth.

ABSTRACT: Studies on the dynamics of holographic pattern formation in photosensitive polymers, gaining deeper insight into the specific material transformations, are essential for improvements in holographic recording as well as in integrated optics. Here we investigate the kinetics of volume hologram formation in an organic cationic ring-opening polymerization system. The time evolution of the grating strength and the grating phase is presented. We found two steps of growth, separated by a depletion of the light diffraction. Capable to explore this growing behavior, a transition-theory of the refractive index contrast is established. Accordingly the growth curves appear to be ruled by the interplay of polymerization and diffusion. Hence the grating formation mechanisms can be qualified as competing effects regarding the contribution to the refractive index change. We investigate the influence of the preparation and exposure procedure on the transition and consider the usability for integrated wave guide functions.

SUBMITTER: Sabel T

PROVIDER: S-EPMC3757355 | biostudies-other | 2013

REPOSITORIES: biostudies-other

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Long Period Grating Mach-Zehnder Interferometer Based Immunosensor with Temperature and Bulk Refractive Index Compensation.

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| S-EPMC9775309 | biostudies-literature

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Project description:A 3D finite element model constructed to predict the intensity-dependent refractive index profile induced by femtosecond laser radiation is presented. A fiber core irradiated by a pulsed laser is modeled as a cylinder subject to predefined boundary conditions using COMSOL5.2 Multiphysics commercial package. The numerically obtained refractive index change is used to numerically design and experimentally fabricate long-period fiber grating (LPFG) in pure silica core single-mode fiber employing identical laser conditions. To reduce the high computational requirements, the beam envelope method approach is utilized in the aforementioned numerical models. The number of periods, grating length, and grating period considered in this work are numerically quantified. The numerically obtained spectral growth of the modeled LPFG seems to be consistent with the transmission of the experimentally fabricated LPFG single mode fiber. The sensing capabilities of the modeled LPFG are tested by varying the refractive index of the surrounding medium. The numerically obtained spectrum corresponding to the varied refractive index shows good agreement with the experimental findings.

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Strong coupling of single quantum dots with low-refractive-index/high-refractive-index materials at room temperature.

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| S-EPMC7679155 | biostudies-literature

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