Optical Pulse Time Spreader and Optical Code Division Multiplexing Transmission Device

摘要

The ratio P/W between the peak value P and the subpeak value W of the autocorrelation waveform, and the ratio P/C between the peak value P of the autocorrelation waveform and the maximum peak value C of the cross correlation waveform are both large. The present invention comprises phase control means of a structure in which an SSFBG 40 having fifteen unit FBGs arranged in series in the waveguide direction is fixed to the core of the optical fiber 36 that comprises the core 34 and cladding 32 . The difference Deltan between the maximum and minimum of the effective refractive index of the optical fiber is 6.2x10^-5. The phase difference of Bragg reflected light from two unit diffraction gratings that adjoin one another from front to back and provide equal code values is given by 2piM+(pi/2) where M is an integer. Further, the phase difference of the Bragg reflected light from two unit diffraction gratings that adjoin one another from front to back and provide different code values is given by 2piM+(2N+1)pi+(pi/2) where M and N are integers.