Philip Jason Stephanou

Cross-sectional dilation mode resonator with very high electromechanical coupling up to 10% using AlN

For the first time in the development of piezoelectric micromechanical resonators, this paper presents a new class of cross-sectional dilation mode resonators (XDMR) that achieve unprecedentedly high electromechanical coupling constant: kt2 up to 10% for aluminum nitride (AlN) based resonators and 19% for zinc oxide (ZnO) based resonators. Detailed discussions on the geometry design, FEM simulation, and process challenge are provided in this paper to give insight on this novel high-kt2 piezoelectric resonator technology and, more importantly, guide the future development of mechanical resonators with coherent 2D/3D mode shapes.

Novel silicon lenses for long-wave infrared imaging

The design, fabrication and performance of a novel silicon lens for Long Wave Infrared (LWIR) imaging are presented. The silicon lenses are planar in nature, and are created using standard wafer scale silicon micro-fabrication processes. The silicon batch processes are used to generate subwavelength structures that introduce spatially varying phase shifts in the incident light. We will show that the silicon lens designs can be extended to produce lenses of varying focal lengths and diameters, thus enabling IR imaging at significantly lower cost and reduced weight and form factor. An optical design program and a Finite-Difference Time-Domain (FDTD) simulation software tool are used to model the lens performance. The effects of polarization anisotropy are computed for the resultant subwavelength structures. Test samples with lenses with focal lengths in the range of 10 to 50 mm were fabricated. The test sample also included a prism structure, which is characterized by measuring the deflection of a CO2 laser beam and compared to theoretical beam deflection. The silicon lenses are used to produce an image on a VGA micro-bolometer array.