Fig. 2: PTAV characterization and optoacoustic sensing in air. | Nature Communications

Fig. 2: PTAV characterization and optoacoustic sensing in air.

From: High spatiotemporal resolution optoacoustic sensing with photothermally induced acoustic vibrations in optical fibres

Fig. 2

a Experimental setup. DAQ data acquisition module, L Lens, PH pinhole. A uniform fibre (b), a side-polished fibre (e) and a partially laser-ablated fibre (h) are used in optoacoustic sensing. c Measured ring-down waveform. Sampling rate: 100 MHz; detection bandwidth: 50 MHz. Inset: temporal signal within the grey box time window. d Acoustic spectrum of the TR21 mode. Inset: measured spectrum at the full frequency scale, in which the TR21 and TR23 modes can be observed. f Measured spectrogram of the side-polished fibre. g Acoustic spectrum at z = 2.05 mm (labelled by the vertical dashed line in (f)). Inset: calculated transverse mode profiles. Arrows represent local displacements. i Spectrogram measured by scanning the PTAV over the step structure. The two vertical dashed lines mark the steps. j Comparison of the variations in the resonance strength of the two resonance peaks at the left edge of the step.

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