Ippei Sawaki

A rotational comb-driven micromirror with a large deflection angle and low drive voltage

We have designed, fabricated, and tested a V-shaped torsion bar for use with a comb-driven micromirror. This torsion bar suppressed undesired sticking of the comb teeth, and enabled a large rotational angle and a low drive voltage. We observed 5-degree rotation of a comb-driven micromirror with a drive voltage of 90 V.

A 2-axis comb-driven micromirror array for 3D MEMS switches

Presents a new architecture of a 2-axis comb-driven micromirror array that combines a large deflection angle in a stationary operation, a low drive voltage, and easy scalability for a 3D MEMS switch. By using an SOI wafer with 100-/spl mu/m thick top and bottom Si layers and a 1-/spl mu/m buried oxide layer and, bulk micromachining with DRIE, we fabricated a 2-axis comb-driven micromirror array with a V-shaped torsion bar and comb teeth. The V-shaped torsion bar that has an optimized spring constant that enables both a large rotational angle and a low drive voltage without creating the undesired pull-in motion of the comb teeth. To implement a 2-axis tilt motion, we fabricated a gold bump for creating a gap under the comb teeth on the electrode substrate and mounted the mirror array substrate onto the electrode substrate by using the flip-chip-transfer technique. We fabricated an 80/spl times/80 switch chip and achieved a +/-5 degree rotation of the 2-axis stationary operation with a 60-V drive voltage.

Crosstalk characteristics of Ti-LiNbO 3 intersecting waveguides and their application as TE/TM mode splitters

Crosstalk characteristics of an intersecting waveguide are presented. Two straight channel waveguides which intersect at an angle of a few degrees on y -cut LiNbO 3 were fabricated by in-diffusion of Ti. Experimental results show that the crosstalk characteristics are determined by the refractive index change profile and the geometry of intersection associated with guided wave modes. In a special case, a TE/TM mode splitter was obtained by using the intersecting waveguide which provides adequate anisotropy by the change in refractive indices. Splitting ratio was 17 and 14 dB for the TE and TM modes, respectively.

Single crystal silicon cantilever-based RF-MEMS switches using surface processing on SOI

This paper describes a novel structure and simple fabrication process for low-loss, low-cost, and high-yield RF-MEMS switches. Our switch has a single crystal silicon (SCS) cantilever, above which are located electroplated bridge electrodes on silicon-on-insulator (SOI) substrates. The fabrication process does not require any complex processes, such as wafer transfer, wafer backside etching, special planarization techniques, or low-stress thin-film formation. The fabricated series switch features a low-loss performance and small size. The overall insertion loss is -0.1 dB and the isolation is -30 dB at 5GHz. The size of the SP4T switch is 1.4 /spl times/ 0.9 mm/sup 2/.

Rectangularly configured 4*4 Ti:LiNbO/sub 3/ matrix switch with low drive voltage

A matrix switch with a novel architecture has been demonstrated. A rectangularly configured 4*4 switch has been designed and fabricated on a 65-mm-long z-cut Ti:LiNbO/sub 3/ chip. The average drive voltage of 16 Delta beta -reversal directional couplers is 9 V for a cross state and 20 V for a bar state. The drive voltage difference of 11 V is about half that of the conventional matrix switch. Drive voltage deviations are within +or-0.5 V. The average insertion loss is 4.7 dB, and deviations for different paths are within +or-0.3 dB, and deviations for different paths are within +or-0.3 dB. The crosstalk of all crosspoint switches is also estimated based on crosstalk output measurements. >

A multi-chip directly mounted 512-MEMS-mirror array module with a hermetically sealed package for large optical cross-connects

A 512 MEMS mirror array module with a hermetically sealed package for large optical cross-connects is constructed by using newly developed multi-chip direct mounting (MCDM) technology and is demonstrated to enable a plusmn5 degree rotation of the two-axis stationary operation under a drive voltage of 160 V, while having a high resonance frequency of 2 kHz

Crosstalk Characteristics of Ti-LiNbO/sub 3/ Intersecting Waveguides and Their Application as TE/TM Mode Splitters

Crosstalk characteristics of an intersecting waveguide are presented. Two straight channel waveguides which intersect at an angle of a few degrees on y-cut LiNbO/sub 3/ were fabricated by in-diffusion of Ti. Experimental results show that the crosstalk characteristics are determined by the refractive index change profile and the geometry of intersection associated with guided wave modes. In a special case, a TE/TM mode splitter was obtained by using the intersecting waveguide which provides adequate anisotropy by the change in refractive indices. Splitting ratio was 17 and 14 dB for the TE and TM modes, respectively.

A multi-step DRIE process for a 128 /spl times/ 128 micromirror array

A multi-step DRIE process for fabricating a vertical comb-driven micromirror array with five different heights was developed. This process was used to fabricate a dual-axis 128 /spl times/ 128 micromirror array with a high resonance frequency.

Detection Of Magneto-Optic Signals Using An External Cavity Laser Diode

We propose the detection of magneto-optic signals using an external cavity laser diode suitable for constructing a small optical head. A magneto-optic medium is used as one of the cavity mirrors. This method is based on detecting the frequency-shift signal, instead of the conventional amplitude-modulated signal, and is expected to raise the signal-to-noise-ratio.

Detection of Magneto-Optic Signals Using a Ring Cavity Laser Diode

We have proposed an external cavity laser diode for a magneto-optic signal detection. However, the signal is not stable enough for optical head application. In this paper, we describe the mechanism of beat signal instability in the external cavity laser diode and propose a new ring cavity configuration. The magneto-optic signal stability is greatly improved over that of the conventional linear cavity.