FABRICATION OF A VARIABLE DIFFRACTION EFFICIENCY PHASE MASK BY MULTIPLE-DOSE ION-IMPLANTATION

Apodized fiber Bragg gratings show reductions in the unwanted sideband s from those of uniform Bragg grating. A phase mask whose diffraction efficiency varied from the center to the ends was fabricated by implan ting a grating pattern in a SiO2 substrate with Si++ and wet etching i n diluted HE The phase mask diffraction efficiency vs ion dose was mea sured. Using this phase mask, apodized Bragg gratings were photoimprin ted into fibers. The sidebands of the apodized fiber gratings were 26 dB below the peak of the central resonance compared to 12 dB for the u niform Bragg grating. The modeled values were 29 and 13.2 dB, respecti vely.