Ultrabroadband near-infrared emission profiling in multicore optical fibers doped with Er3+ and Yb3+/Tm3+/Ho3+ ions

This paper presents novel multicore fibers with broadband emission in the 1.4-2.1 μm range. Based on our previous work with barium gallo-germanate glasses and fibers, the 4 and 11-core fiber structures, each containing core glasses doped with Er³⁺ and Yb³⁺/Tm³⁺/Ho^3+, were developed. Our efforts have resulted in flat emission in 3 dB and 10 dB bands, achievable under excitation at 796 nm, 808 nm, 940 nm, and 980 nm. The measured emission spectra of these fibers are described as a superposition of emission bands from each individual core, corresponding to the transitions of Er³⁺, Tm³⁺, and Ho³⁺ ions. Our method demonstrates the potential of emission profiling in multicore optical fibers as a new way to construct eye-safe broadband fiber sources.