Figure 2. a) Schematic diagram of the strain-sensing system
based on the optical microfiber coupler. b) Simulation diagram of
strain-CR response under different coupling lengths. c) Simulation
analysis of sensitivity under different coupling lengths and radii. d)
Experimental results of strain-CR response of the microfiber coupler
with radii of 1.0 μm, 1.5 μm and 2.0 μm, respectively. e) Magnified plot
of the area outlined in black in (d). f) CR periodic change and loss
variation of the microfiber coupler under strains. g) Time-dependent
strain-CR response produced from optical microfiber coupler sensor
during periodic stretch and release over 10 000 cycles with 0.12%
strain. h) Time-dependent strain-CR response produced from a loudspeaker
at a frequency of 3 kHz. i) Frequency spectrum of the strain-CR response
waveform.