The Design Of Phononic Crystals Acoustic Sensors

In recent years,with the recent developments in micro-phononic crystal fabrication and testing,the anomalous physics properties of phononic crystal and the new useful applications based on phononic crystal have received more and more attentions.Especially the development of high-Q liquid sensors with high resonant frequency in phononic crystal(PC)slabs becomes very urgent for realization of phoxonic crystal sensing combining the acoustic sensing and optical sensing in one device with two independent material properties involved.The unsolved problems include the problems of acoustic energy focusing in detected liquids,increasing the efficiency of transmitting,improving the Q-factor,and realizing the integration of phononic crystals and photonic crystals.These problems have received active attention in the world.We have performed deep research around these problems.We have first studied the innate law of energy distributions and transmission spectrum for two-component and three-component solid-based phononic crystals composing liquid circular cylinders and the influence of resonance cavity coatings on the location and sharpness of transmission peaks.We have proposed to study and develop phononic crystals sensors in view of the integration of photonic crystals and phononic crystals,and chose silicon as the solid matrix,which is more common and convenient in practical implementing applications.We have presented the band structures of perfect PCs composing square cylinders and of PCs with defect chain to obtain a large background PBG and a few useful flat defect passing bands falling in the PBG.We have firstly proposed an acoustic system to achieve acoustic extraordinary resonance transmission by asymmetrically exciting the Lamb modes in silicon phononic crystal slabs with wedges-like structures obtained by inserting the defect chain into the perfect PCs composing square cylinders.The extraordinary transmission spectra for different liquids filled have also been studied to reveal the tunable properties of the achieved acoustic extraordinary resonance transmission.Optimization of the liquid cavity geometry has been further performed to improve the performance of the extraordinary resonance transmission peaks.The corresponding Q-factor is calculated up to 5776.The results presented above have promised to pave the way to flexible manipulation of the effective acoustic path length and transmission performance,and the striking features of the proposed acoustic system may make it to be excellent candidates for tunable filtering and sensing applications.