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Recently, intense research on single-mode rare-earth doped fiber lasers and amplifiers[fl has led to the development of a range of active devices. The possibility of ion-doping of standard integrated-optic waveguides has recently allowed the demonstration of Nd- and Er-doped single-mode channel waveguide lasers in single crystal Ti:LiNbO3 waveguides[12] and various glass waveguides[35]. However, there are a number of intrinsic limitations associated with these material systems. First, glass waveguides have no electrooptic(EO) effect therefore, an active device cannot be made using these substrates. Second, LiNbO3 waveguides have significant walk-off between the refractive indices of microwave and optical waves. Consequently, the modulation speed of the EO modulator, which serves as the input signal generator for the waveguide amplifier, is limited to 4O GHz[6]. Third, the waveguide fabrication methods for LiNbO3 and glass substrates are not universal. They are not transferable to other substrates. For instance, Si and GaAs are the most frequently used substrates for optoelectronics. LiNbO3 and glass waveguide lasers cannot be implemented on these substrates as amplifiers without violating the monolithic integration preference. Photo lime gel-based polymer waveguide is an excellent guiding medium due to its wide transmission bandwidth(300nm to 2700nm). The GRIN characteristic of this material[7] allows the formation of high quality(loss <0.1 dB/cm) single-mode passive and active devices on an array of substrate[81. In this paper, we report a graded index(GRIN) polymer waveguide amplifier working at 1 .O6im wavelength using Nd-doped photolime gel as the active medium. Fluorescent spectrums at 1 .32im (Nd3doped) and at 1.56 im (Er3-doped) were also observed and the results are shown in Figs.l and 2, respectively. The polymer introduced is soluble in water. As a result, the chemical compounds containing rare earth ions(REIs) can be mixed with the host polymer as long as they are hydrophilic. But the doping concentrations should be below the level of microscopic clustering[5] which quenches the active ions. There are other quenchers which shorten the lifetime of metastable states of active ions. The most serious quenchers are the admixed 0-H groups whose concentration must be less than 3-5x10'8/cm3 [4] for glass waveguide amplifier. The existence of 0-H groups generates a number of intermediate states between the transition states. Such states, primarily from water molecules, significantly reduce the lifetime of metastable states. The general rule of thumb is that the lifetime of the excited state will be temperature dependent if the gap is less than ten times the effective phonon frequency and completely quenched if less than four times[5I. Experiment results will be presented at the conference.
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