The Influence Of Tilting Fiber Grating On Property Of Optical Information Transmission

Fiber grating is give by UV light, refractive index period construct is bring about core axis, is important optoelectronic device in optical communication. The effect of tilt on optical transmit characteristics in fiber grating, so on optical communicational characteristics.The effect of tilt on mode couple coefficient, reflectivity, transmission and dispersion characteristics of optical communicational system is discussed from mode coupling equation of fiber grating in the paper, numerical calculated by transmit matrix and Matlab program.The result is give from the paper that the effect of tilt on reflective spectrum is very small and the figure of reflective spectrum hasn't evidence change when tilt angle is very small (lower than 0. 2~0). When tilt angle isn't very small (lower than 0. 8~0), it is evidence effect of tilt to reflective spectrum and dispersion characteristics. As increase of tilt angle, the coupling coefficient will be decreased, reflect light decrease, reflectivity and band wide decrease, the fluctuation in optical spectrum decrease too. The period increase along with length direction by tilt, the range of delay is expand, dispersion increase. When tilt angle is very big (more than 6°), the band wide of reflective spectrum decrease, the most reflectivity will decrease, and present period change as tilt angle decrease. The tilt is arose by fabricating in transmission fiber grating, may be equivalent straight tilt square chirp grating. When bent curvature radius decrease, tilt angle of equivalent straight tilt grating increase, grating striation visibility reduce, mode coupling coefficient of core and cladding mode decrease, resonance apex decrease. When bend radius less (lower then 0.4 time grating length), transmission rapid decrease, transmit spectrum fluctuate and delay decrease as bend radius decrease, make clear that the less of grating bend radius, the bigger of power attenuate, the less of dispersion.The results by the paper show that when grating tilt (include equivalent tilt of bent), the optical information transmit characteristics in fiber gratings have changed, reflectivity, The numerical calculation show, the evidence effect of tilt on optical characteristics of grating when tilt angle is upward 0. 8~0, bend radius of equivalent tilt lower than 0.4 time grating length, transmission, band wide and dispersion decrease. If tilt grating used of optical communication device, these device characteristics will evidence changed. In fabricating and using, the tilt must be restricted in above confine for ensure transmit quality of optical communication system.