Fig. 1. Structure of (6+1)×1 signal combiner and cross sections of TFB and output fiber

Fig. 2. Transmission range of outer ring input beam on TFB cross section

Fig. 3. Input fiber diameter versus taper ratio

Fig. 4. Proportion of three modes when TR is 0.2‒1.0

Fig. 5. Weld images of TFB. (a) Cross section of TFB; (b) installation diagram of welding machine; (c) side view of weld point

Fig. 6. Experimental setup for combiner performance test

Fig. 7. Relationship between input power ratio and temperature

Fig. 8. M² test data at central port

Fig. 9. M² test data at outer ring port 2

Fig. 10. Experimental diagrams of environmental resistance test. (a) Experimental sample at low temperature of -30 ℃; (b) experimental sample at high temperature of 70 ℃; (c) efficiencies of each port in three cases