Optical parametric amplification in composite tellurite-fluorophosphate fiber

We present the design, dispersion calculations and tailoring, and simulation of the parametric gain in the composite tellurite-fluorophosphate glass fiber. The fiber has the tellurite core subsequently surrounded by fluorophosphate and tellurite claddings. Thermal properties of the tellurite and fluorophosphate glasses match, depicting the feasibility of the fabrication of the fiber under controlled environment. The composite fiber introduced here has the advantage of easy handling over the fiber tapers or the air cladding tellurite nanofibers. With our analysis we observe that the fluorophosphate and the tellurite cladding thickness along-with the fiber core diameter, have control on the dispersion and the parametric gain. The wavelength band, over which the dispersion is anomalous, increases with increasing tellurite core diameter. For longer wavelengths, increasing the fluorophosphate cladding thickness causes increase in the anomalous dispersion bandwidth and further flattening of the dispersion curve. The slope of the dispersion curve near the zero dispersion wavelength (ZDWL) is greatly reduced for thicker outer tellurite ring claddings. It is possible to design zero flattened dispersion fiber or the fiber providing two ZDWLs in the communication band, which can generate broadband parametric amplification. The gain obtained has strong bandwidth dependence on the dispersion slope. We study the effects of the fiber length, pump power, and pump detuning from the ZDWL, on the parametric amplification. With multiple pumping with proper selection of the pump wavelengths, the parametric amplification process can generate ultra flat, broadband amplifiers as the dispersion provided by the composite fiber is anomalous over a wide bandwidth.