Seeking shear waves in liquids with picosecond ultrasonics

Solitary surface acoustic waves and bulk solitons in nanosecond and picosecond laser ultrasonics.

Recent achievements of nonlinear acoustics concerning the realization of solitons and solitary waves in crystals and their surfaces attained by nanosecond and picosecond laser ultrasonics are discussed and compared. The corresponding pump-probe setups are described, which allow an all-optical contact-free excitation and detection of short strain pulses in the broad frequency range between 10 MH...

Picosecond Ultrasonics: a Technique Destined for BAW Technology

Since the 80’s, Bulk Acoustic Wave (BAW) resonators technology has been seeing a rapid expansion, due to its potentials in terms of performances and integration for Radio-Frequency (RF) filtering. The control of the frequency is a challenging question for the mass production of such devices, and passes through an accurate control of mechanical properties of the whole stack. The picosecond ultra...

Thin-film Thermal Conductivity and Thickness Measurements Using Picosecond Ultrasonics

A method utilizin g picosecond u ltrason ics, combin ed with a pump-probe therm oreflectance techn iqu e, for the sim u ltan eou s m easu rem ent of thin -film th ickness and thermal condu ctiv ity norm al to the su rface is presen ted. Th is techniqu e is a non con tact m ethod that is u sefu l for determ in in g thermophysica l properties of film s with th ickness grad ien ts or for film s in...

Nondestructive detection of titanium disilicide phase transformation by picosecond ultrasonics

We demonstrate that picosecond ultrasonics is a sensitive nondestructive probe of the formation of TiSi, from the reaction of titanium films on silicon annealed at temperatures of 300-800 “C. From the measured change in optical reflectivity, the responses due to electronic excitation, acoustic echoes, and thermal coupling to the underlying Si are resolved. The results show significant differenc...

Waves in bubbly liquids with phase change