Ushio Sangawa

Packaging using microelectromechanical technologies and planar components

A novel millimeter-wave packaging structure was developed in which a micromachined low-loss planar component and flip-chip devices were integrated on a silicon substrate. A low-loss planar filter was achieved on a 7-mm-square silicon substrate employing an inverted microstrip line and a unique resonator. High attenuation in the stopband was also obtained by introducing a pole control technique. Fabrication of a compact K-band receiver front-end incorporating a built-in filter was realized using multilayered benzocyclobutene (BCB) and flip-chip bonding techniques. Furthermore, we propose an alternative BCB suspended structure and demonstrate a planar antenna for Ka-band applications. These technologies bring to reality high-performance compact packaged systems in millimeter-wave region applications.

The Origin of Electromagnetic Resonances in Three-Dimensional Photonic Fractals

After a report on strange electromagnetic resonances emerging in an isotropic paraelectric Menger sponge (MS) now known as a photonic fractal, vigorous studies began to reveal their properties. However, the mechanics of how the resonances occur is still unknown. This report focuses on the flndings that the resonances can be perturbation-theoretically identifled as those originally occurring in an isolated dielectric cube, and that they arise within band gaps and uncouple with Bloch modes for a certain multiperiodic lattice. This interpretation is justifled by the fact that the MS can be considered as a cube embedded in the lattice rather than the outcome of conventional recursive fractal structuring operations. An experimental formula for resonance conditions already reported can be derived from this interpretation.

Novel air-borne ultrasonic sensor using nanofoam and a laser Doppler vibrometer

We propose a novel airborne ultrasonic sensor, using nanofoam and a laser Doppler vibrometer that can operate over a wide frequency range and provide high sensitivity. Nanofoam is a porous material made by sol-gel process and has low density, low elasticity, and extremely low acoustic impedance. These properties enable nanofoam to take in acoustic energy from ultrasonic waves. In addition, nanofoam has a good optical transmittance. Because optical detection can be much faster than detection period in the sound frequency range, it has been considered that a wideband ultrasonic sensor can be realized by the combination of nanofoam and laser measurement. In this report, we describe fabrication of the proposed sensor and determine its basic properties.

Millimeter-wave Transceiver MCM Usig Multi-layer BCB with Integrated Planner Antenna

A novel millimeter-wave transceiver MCM using multi-layer BCB was proposed. This MCM is based on a glass substrate laminated with three layers of BCB thin film, enabling four-layer 3-D circuitry. We report two different Ka-band MCMs of this structure; namely, a flip-chip assembled 28 GHz transceiver MCM integrating four MMICs of independent functions, and a 38 GHz receiver MCM with built-in four-element slot antenna array and flip-chip assembled MMIC.

Packaging using MEMS technologies and planar components

Three-dimensional millimeter-wave IC applying multi-layer BCB thin film and silicon micromachining technology was developed. Low loss characteristics were achieved by applying micromachining technology, despite being a quasi-planar structure, and a K-band filter was developed. Moreover, manufacture of the receiver front-end with built-in filter integrated into one package was realized by using flip-chip bonding techniques. Furthermore, we proposed an alternative BCB suspended structure and demonstrated a Ka-band antenna for the proposed package.

Palm sized airborne ultrasonic sensor with nanofoam acoustic lens and homodyne interferometer

We propose an optoacoustic airborne ultrasonic sensor consisting of a 633-nm He-Ne laser, an Si PIN photodetector, and a sensor head. The device has a sensitivity of 92.7 dB SPL (Sound Pressure Level) for acoustic signal inputs of single 40-kHz pulses, and it exhibits wideband receiving properties because of excluding mechanical moving elements such as diaphragms or voice coils from the sensor. The sensor head, which incorporates an acoustic lens, is made of nanoporous silica in which the sound speed is 50 m/s. Also, it has tapered aperture fields designed to improve its focusing properties and achieve high sound pressure at its focal point, and an integrated Mach-Zehnder homodyne interferometer that translates the pressure into the intensity of optical interference light. The entire device occupies a volume of 65×70×70 mm3. In addition, we discuss the design methods and derive the equations for the acoustic lens. Finally, a strategy to achieve more stable and highly sensitive optoacoustic sensors is also discussed.