Fig. 1. (a) Schematic diagram of tapered pump fiber parameters; (b) Schematic diagram of the pump-signal coupling process; (c) Diagram of combiner test device

Fig. 2. (a) Evolution diagram of combiner output power with pump power increasing; (b) Evolution diagram of combiner holder’s temperature with pump power increasing

Fig. 3. Mid-infrared all-fiber superfluorescence fiber source experimental device

Fig. 4. (a) Evolution of mid-infrared superfluorescence spectra at the pumping power of 0.39-1.8 W; (b) Evolution of mid-infrared superfluorescence spectra at pump power of 1.8-5.6 W

Fig. 5. Energy level structure diagram of Er³⁺

Fig. 6. (a) Evolution diagram of backward output power with pump power increasing; (b) Evolution diagram of forward output power with pump power increasing