In this paper, we propose and demonstrate the use of multilayered (laminated) waveguides for increasing the available gain spectrum of sol–gel amplifiers. Experimental investigations of the effects of phosphorus codoping on the amplifier spectral characteristics and fluorescence decay are also presented. We demonstrate that the shape of the erbium emission cross section, for aluminophosphosilicate amplifiers, has a minor dependence on the amount of phosphorus doping and that spectral benefits are only achieved for aluminosilicate amplifiers, albeit with low levels of erbium inversion. Laminated amplifiers, consisting of alternating layers of two compositions, are shown to display novel spectral characteristics that cannot be obtained by the use of single composition cores. Internal gain, which is demonstrated for this device, also suggests that erbium inversion can be maintained at relatively high levels. Experimental results are supported by numerical analysis, and a 20-nm bandwidth increase is observed for laminated amplifiers, with gain levels up to 1.4 dB/cm indicated, when processing conditions are optimized.
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