Phase-shifted fiber Bragg grating filters based on counter-propagating cladding modes coupling.

In this paper, we comprehensively analyze counter-propagating cladding mode assisted phase-shifted fiber Bragg gratings (FBGs) and propose an ultra-narrow bandwidth laser line filter based on such gratings. Full vector modal analysis has been used to obtain the mode guiding and its coupling characteristics. We show that the transmission spectrum of the counter-propagating cladding mode assisted FBGs can be tailored by incorporating single or multiple phase shifts along the grating length.

Ultra-narrow linewidth transmission filters based on the cladding mode assisted Fabry-Perot effect in a planar waveguide.

We propose and analyze a counterpropagating cladding mode assisted tunable frequency Fabry-Perot interferometer formed by a Bragg grating (BG) cavity in a liquid crystal coated planar optical waveguide. A full vector modal analysis has been used to obtain the transmission spectra of the individual Bragg reflectors, and the cavity effects have been incorporated by employing a suitable phase matrix. We show that the cavity resonances that appear from two fiber BGs forming a resonator can be efficiently explained by incorporating appropriate phase shifts in one BG grating period.

Sensing characteristics of grating assisted counterpropagating cladding modes in optical fibers.

In this paper, using full vector modal field analysis, we present physical parameter sensing, e.g., temperature, axial strain, bulk refractive index, and affinity sensing characteristics of counterpropagating cladding modes in optical fibers.