239417.fig.024
Figure 24: Transmission and reflection spectra of a uniform Bragg grating in a germanosilicate-doped core photonic crystal fibre with and without an applied acoustic wave with frequency 82.3 kHz. At this frequency, a central phase shift is introduced and the band gap broadens. This change was sufficient to generate >10 dB signal contrast when switching a tuneable laser on and off [89].