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This study focuses on the tilted fiber Bragg gratings. The paper describes the method of their inscription into optical fiber using the Talbot interferometer and KrF excimer laser system. The method allows precise selection of the resonant wavelengths and tilt angles of the created structures in a wide range of values. In course of the study, an original method was proposed for inscription of a superposition comprising two structures being identical in parameters but having the opposite tilt angles of grating strokes relative to the optical fiber cross-section. The described method makes it possible to compensate the decrease in the reflective efficiency of fiber Bragg gratings with an increase in their tilt angle. [ABSTRACT FROM AUTHOR]

Radiation-mode coupling is stronger and more efficient in tilted fiber Bragg gratings than in other fiber gratings; it has good advantage in such fields as optical communication and optical sensors. A simplified coupled-mode theory (CMT) approach is proposed for what we believe to be the first time, whose validity is demonstrated by comparing its simulation results with that of the complete CMT equations. With the simplified CMT approach, a theoretical spectral analysis of coupling from core mode to counter-propagating radiation modes in reflective tilted fiber Bragg gratings is presented. The influence of grating length, refractive index modulation amplitude and tilt angle is exhaustively investigated on the transmission spectrum characteristics. The different dependences between s-polarized and p-polarized radiation-mode coupling on grating tilt angle are discussed, and the coupling strength of 45°-tilted gratings shows the greatest polarization dependence with the limitation of backward-propagating radiation-mode coupling. [ABSTRACT FROM AUTHOR]

The polarization properties for tilted fiber Bragg gratings (TFBGs) are investigated theoretically based on coupled-mode theory and Mueller matrix method. The expression of wavelength-related polarization-dependent loss (PDL) for TFBGs with different tilt angles is derived and calculated. Simulation results are compared, and the results indicate that the polarization capability of TFBGs with 45° angle is stronger than other TFBGs with smaller angles. The degree of polarization for unpolarized light passing TFBGs is also simulated to further evaluate the polarization properties for various tilt angles. In addition, the relationship between physical parameters of a TFBG and its polarization capability is discussed. [ABSTRACT FROM AUTHOR]