Characteristics of bandwidth, gain and noise of a PbSe quantum dot-doped fiber amplifier

Different from existing erbium-doped fiber amplifiers (EDFAs), PbSe quantum dot rather than conventional erbium ion is adopted as dopant in the fiber, due to its favorable emission–absorption spectra. A three-level system is proposed based on the observed emission–absorption spectra of the PbSe quantum dot. Scattering loss arising from its high refractive index and nanometer size is discussed thereafter. By a steady-state approximation, populations of the levels are expressed as an analytical function. Propagation equations of the light power with different frequencies are thereby solved by utilizing a numerical method in a single-doped case. The signal gain, bandwidth and noise of the PbSe quantum dot-doped fiber amplifier (QDFA) are estimated for different pumping powers in a single-mode condition. Depending on the emission-peak wavelength and the spectral width, the proposed QDFA can function on a long-wavelength band, with a wider bandwidth and lower noise than EDFAs.