Numerical Analysis of 3.92 μm Dual-Wavelength Pumped Heavily-Holmium-Doped Fluoroindate Fiber Lasers

Abstract

The 3.92 μm laser pumped by 888 and 962 nm sources in a high concentration holmium-doped InF3 fiber is predicted and verified by simulation for the first time. Most parameters involved in the numerical model are taken from published results about the fundamental properties of holmium in fluoroindate glasses. The remaining unknown parameters are estimated from published 888 nm single-wavelength pumping experimental data. Simulated results indicate that the dual-wavelength pumping system can give a more powerful output than the single-wavelength pumping system when the total launched power is at the same level. The laser output as a function of the power of each source, as well as several macro factors such as fiber length and output coupler reflectivity, are investigated to find the best condition for higher output. To evaluate the importance and influence of the known interionic energy transfer processes, we analyze the corresponding laser output and changes of population densities of laser upper and lower levels by isolating each process. This investigation gives a preliminary insight into the 3.92 μm laser performance and interionic dynamics of the dual-wavelength pumping system in holmium-doped InF3 fibers.