Simple optic fibre microphone based on hetero-core spliced fibre structure

A novel and simple fibre optic microphone (FOM) based on hetero-core fibre structure is presented. A multimode-singlemode fibre structure attached to an aluminium membrane is employed as an acoustic sensor. The sound vibrations are detected by measuring the change of intensity of the transmitted light coupled from a multimode fibre to a singlemode fibre because of the deformation of the splicing section in the multimode-singlemode fibre structure. Experiments are carried out to study the performance of the proposed hetero-core fibre microphone. The results show that the multimode-singlemode (MS) structure based FOM can detect sound signals within the frequency range 300 Hz-20 kHz and shows a good sensitivity especially when sound frequency is below 12 kHz.