Monolithic phononic crystals with a surface acoustic band gap from surface phonon-polariton coupling.

We theoretically and experimentally demonstrate the existence of complete surface acoustic wave band gaps in surface phonon-polariton phononic crystals, in a completely monolithic structure formed from a two-dimensional honeycomb array of hexagonal shape domain-inverted inclusions in single crystal piezoelectric Z-cut lithium niobate. The band gaps appear at a frequency of about twice the Bragg band gap at the center of the Brillouin zone, formed through phonon-polariton coupling. The structure is mechanically, electromagnetically, and topographically homogeneous, without any physical alteration of the surface, offering an ideal platform for many acoustic wave applications for photonics, phononics, and microfluidics.

Low power consumption integrated acousto-optic filter in domain inverted LiNbO3 superlattice.

We report on an integrated acousto-optic filter in domain inverted LiNbO3 using a coplanar electrode configuration, which can achieve complete optical switching at electrical powers as low as 50 mW. These values are more than one order of magnitude lower than previously reported results [Opt. Lett. 34, 3205 (2009)]. In order to design the low power consumption devices, we have calculated surface acoustic wave excitation, propagation and acousto-optic interaction in the domain inverted LiNbO3 superlattice using scalar approximation and FEM analysis. Results from both modeling techniques are in good agreement with the experiments, including direct measurement of the acoustic displacement using laser interferometry and acousto-optic performance.

Integrated acousto-optic polarization converter in a ZX-cut LiNbO(3) waveguide superlattice.

We report an integrated acousto-optic polarization converter exploiting a novel surface acoustic superlattice (S-ASL) transducer. The S-ASL transducer is made of a ZX-cut periodically poled lithium niobate (PPLN) crystal with uniform coplanar electrodes for surface acoustic wave (SAW) generation. For a PPLN period of 20 microm the SAW is excited at an rf of about 190 MHz, while the phase matching occurs at an optical wavelength of around 1456 nm. The measured mode conversion efficiency of 90% at an input rf power of 1 W and the 3 dB optical bandwidth of 2.5 nm confirm the confinement of the SAW between the electrode gap and the constructive interaction along the whole 10 mm electrode length.