Study on the frequency dependence of lateral energy leakage in RF BAW device by fast-scanning laser probe system

Frequency domain analysis of lamb wave scattering and application to film bulk acoustic wave resonators

“…7(a) that the strongly electrical excited thickness extensional branch s 1 (−) is mostly scattered to the s 0 mode below the resonance frequency. This supports the laser measurement results reported by Wu et al [18], where this strong scattering at the quasi-free edge already could be observed and the amplitude of higher-order lamb modes is much smaller above F s1c than below, indicating that they are mainly excited by mechanical mode conversion from s 1 (−).…”

“…1). These quasi-free edges can be regarded as less important for direct energy losses, but probably have to be considered in terms of mode conversion as has been observed by laser interferometer measurements [18].…”

Power deduction from surface fields in multilayer waveguides

“…The general intensity of observable energy leakage is higher below the main resonance f = 2.03 GHz than above, which is in good accordance with the laser-probing investigation of practical Fbar structures [9].…”

“…laser probes have commonly been used for the experimental investigation [7]- [9]. Whatever method of analysis was used up to now, the lateral propagating modes in terms of energy they carry were merely investigated qualitatively, because of their complex behavior.…”

“…The first step is its decomposition into contributions of propagating eigenmodes. This can be accomplished by applying a fast Fourier transform (FFT) to the field distribution as demonstrated in processing the data obtained by a laser probing system [9]. The next step is to convert the amplitude of each mode into its carrying power.…”