Gaussian profile fiber Bragg gratings exhibit narrow-bandwidth transmission peaks with significant group delay at the edge of their photonic bandgap. We demonstrate group delays ranging from 0.2 to 5.6 ns from a 1.2 cm structure. Simulations suggest such a device would be capable of enhancing the field intensity of incoming light by a factor of 800. Enhancement is confirmed by photothermally induced bistability of these peaks even at sub-milliwatt input powers with as much as a four-fold

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... nce in the magnitude of their responses. The strong field intensities of these modes could significantly enhance desired nonlinear optical responses in fiber, provided the impact of absorption is addressed.