Wavelength-interleaved OADMs incorporating optimized multiple phase-shifted FBGs for fiber-radio systems

We demonstrate that a single fiber Bragg grating (FBG)-based optical add-drop multiplexer can be used to improve the optical spectral efficiency in a mm-wave WDM-fiber wireless network. The technique employs wavelength interleaving in conjunction with optical single-sideband modulation, together with a single multiphase-shifted fiber Bragg grating. Wavelength optical add-drop features are also demonstrated using the grating, and our results show the performance of the novel grating in terms of channel isolation and add-drop functionality. We perform simulations to optimize placement of the phase shifts when an apodization profile is applied to the grating, in an attempt to minimize in-band and out-of-band transmission-amplitude ripples. Experiments are performed using cascade configurations both with the apodized gratings with optimal phase-shift positions and with the original unoptimized gratings. The experimental results demonstrate how these novel gratings can be used in fiber-radio networks incorporating multiple optical add-drop multiplexers.