RESUMO
In this study, a Si defect structure was added into the silica network in order to activate the bismuth and silica structure active center. TD-DFT theoretical simulations show that the Bi and Si ODC(I) models can excite the active center of the E-band at 1408â nm. Additionally, the Bi-doped silica fiber (BDSF) with improved fluorescence was fabricated using atomic layer deposition (ALD) combined with the modified chemical vapor deposition (MCVD) technique. Some tests were used to investigate the structural and optical properties of BDSF. The UV-VIS spectral peak of the BDSF preform is 424â cm-1, and the binding energy of XPS is 439.3â eV, indicating the presence of Bi° atom in BDSF. The Raman peak near 811â cm-1 corresponds to the Bi-O bond. The Si POL defect lacks a Bi-O structure, and the reason for the absence of simulated active center from the E-band is explained. A fluorescence spectrometer was used to analyze the emission peak of a BDSF at 1420â nm. The gain of the BDSF based optical amplifier was measured 28.8â dB at 1420â nm and confirmed the effective stimulation of the bismuth active center in the E-band.
RESUMO
In this study, PbS/Er co-doped fibers (PEDFs) were fabricated by atomic layer deposition (ALD) combined with modified chemical vapor deposition (MCVD). A pumping scheme based on two-photon absorption at 1310â nm of PEDF is proposed for L + band amplification. Through the theoretical analysis, the local environment of Er3+ is changed due to the co-doping of PbS, which improves the two-photon absorption efficiency near 1300â nm. Compared with the 980â nm pump, the PEDFs excited by the 1310â nm pump show better amplification performance in the L + band. And in a bi-directional pumping system, PEDF achieves over 22â dB of gain in the whole L band. In particular, the bandwidth of over 20â dB gain was extended to 1627â nm with a noise figure as low as 4.9â dB. To the best of our knowledge, this is the first time that a high-gain bandwidth of L band amplification has been extended to 1627â nm. The results of unsaturated loss also show that PbS co-doping improves the two-photon absorption efficiency of PEDF to broaden the amplification bandwidth of L + band. These results demonstrate that an effective L + band amplification method is practically provided for future ultra-wideband optical communications.