OPTICAL PULSE TIME SPREADING UNIT AND OPTICAL CODE-DIVISION MULTIPLEX TRANSMISSION DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an optical pulse time spreading unit such that the ratio P/W of a peak value P and a sub-peak value W of an autocorrelation waveform and the ratio P/C of the peak value P of the autocorrelation waveform and a maximum peak value C of a cross-correlation waveform are both large.;SOLUTION: Disclosed is a phase control means in such structure that an SSFBG 40 having 15 unit FBGs arranged in series along a waveguide direction is assembled in a core of an optical fiber 36 comprising the core 34 and a clad 32. The difference Δn between maximum and minimum effective refractive indexes of the optical fiber is 6.2×10^-5. The phase difference between Bragg reflected lights from two unit diffraction gratings which are adjacent in the front-rear direction and impart equal code values is represented as 2πM+(π/2), where M is an integer. Further, the phase difference between Bragg reflected lights from two unit refraction gratings which are adjacent in the front-rear direction and impart different code values is represented as 2πM+(2N+1)π+(π/2), where M and N are integers.;COPYRIGHT: (C)2006,JPO&NCIPI