A. Bhatti et al., Optical response of an all-fibre acoustooptic phase modulator using aluminium nitride coating, OPT COMMUN, 176(4-6), 2000, pp. 355-363
For the first time we present results on an all-fibre acoustooptic phase mo
dulator using aluminium nitride (AlN) thin film as the piezoelectric coatin
g. Two-dimensional axisymmetric finite element analysis was employed to det
ermine the response of the modulator over a wide frequency range from 10 kH
z to 700 MHz. Phase shifts of 0.823 rad/V/m in the low frequency region and
0.374 rad/V/m in the high frequency region were observed. At frequencies h
igher than 28 MHz the response is dominated by radial resonances of the fib
re-coating composite. A theoretical investigation of the acoustic impedance
showed that there is good impedance matching between the AlN piezoelectric
coating and the glass fibre resulting in a high acoustic energy transfer o
f similar to 82% at the coating-fibre interface. (C) 2000 Elsevier Science
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