Patent ID: 8331785
Filing Date: 2012-12-11
Classification: H04J

Abstract:
1. An optical pulse time spreading apparatus which comprises first to U-th optical pulse time spreading units each outputting a chip pulse sequence having N chip pulses from a first to an N-th chip pulse arranged in order on a time axis by time-spreading an input optical pulse, where N is an integer of two or greater and U is an integer of one or greater satisfying that U≦N, wherein each of said first to U-th optical pulse time spreading units comprises a superstructured fiber Bragg grating (SSFBG) comprising N unit fiber Bragg gratings (FBGs); an interval between adjacent ones of said unit FBGs arranged in a p-th optical pulse time spreading unit, where p refers to all integers of from 1 to U, and a Bragg reflection wavelength of said unit FBGs in the p-th optical pulse time spreading unit are set such that spectra of first to U-th chip pulse sequences respectively output from said first to U-th optical pulse time spreading units are different from each other; and the Bragg reflection wavelength λ for when U is an odd number, where k is an integer satisfying that |k|<U/2, for when U is an even number, where k is an integer satisfying that |2k+1|/2<U/2, wherein a Bragg frequency ν wherein an interval Δν and wherein the interval between adjacent ones of the unit FBGs arranged in said p-th optical pulse time spreading unit and the Bragg reflection wavelength of the unit FBGs in the p-th optical pulse time spreading unit are set such that a phase difference Φ between chip pulses reflected from adjacent unit FBGs of said p-th optical pulse time spreading unit is given by the following equation (4): where λ