Acousto-optic intensity modulation on glass-integrated optic
Résumé
An elastic beam of waves in the Megahertz range, generated using a PZT ceramic, crosses one arm of an integrated Mac-Zehnder interferometer realised by ion-exchange in a glass substrate. Elastic waves modify locally the refractive index of glass. A laser beam of 0.83 μm wavelength is injected into the interferometer. For a sine excitation voltage of 7 volts of the piezoelectric transducer, the variation of the optical intensity measured at the interferometer output is greater than 20% of the intensity observed without elastic waves. Refractive index variation of 9.4×10-7 were obtained. The optical intensity observed at the output of the interferometer varies at the frequency of the piezoelectric crystal excitation. A model taking into account the elastic and the optical effects is proposed. This model allows the optimisation of the piezoelectric transducer in order to obtain the maximum of elastic strain at the position of the optical waveguides. The theoretical results obtained with the model are in accordance with the experimental results.