Teiichi Suzuki

a-Si:H TFT Driven Linear Image Sensor

A new contact type linear image sensor, which has 8.5 inches in length and 300 dot/inch, has been developed. By using a thin film transistor (TFT) array as a switching device, it requires only one IC chip compared with 20 ICs in conventional sensor. The new sensor integrates a-Si:H photodiode (PD) array, a-Si:H TFT array, multiplex circuits and an analog multiplexer on a single substrate. The TFT has an inverted staggered structure and amorphous silicon nitride (SiNx) is used as a gate insulator. The PD has a Cr/a-Si:H/ITQ sandwich structure and each PD is completely isolated by photolithography. In the multiplex circuits, a ground line is inserted between each signal line to reduce a capacitive coupling between them. A new custom LSI has also been developed. It has 64-ch input terminals to detect small signal with amplification and 41-ch output terminals to control the gates of TFT array. The sensor with the new LSI has achieved 2MHz clock frequency operation and proved to be used as a high speed device.

Fabrication of a Hemi-Paraboloidal Solid Immersion Mirror and Designing of an Optical Head with the Mirror

A hemi-paraboloidal solid immersion mirror (HP-SIM) was for the first time fabricated with the electrolytic in-process dressing (ELID) grinding technology. By improving the surface deviation and roughness of the HP-SIM to the order of ±0.3 µm and 4 nm, the spot size (FWHM) of 0.22×0.26 µm was obtained in the blue light concentration with the HP-SIM though fairly large side lobes were observed. A small-sized optical head was also designed with the HP-SIM, a pair of collimating lenses, and laser diode, which height can be reduced to 1 mm. Diffraction limited concentration is expected with the HP-SIM optical head, though the accuracy of less than ±1 µm is required for the alignment of the LD to the collimating lenses for both X and Y directions.

10-Gb/s × 12-ch downsized optical modules with electrical conductive film connector

We demonstrate 10-Gb/s/ch operations of high-density, low-cost 12-channel optical modules for optical interconnections. These optical modules that we developed are designed to be pluggable into cards with an electrical connector. These pluggable modules will enable cards to be manufactured much more easily since they allow the manufacturing processes of optical modules and cards to be separated. An electrical connector with a clamp spring is used to connect a ceramic substrate with a printed circuit board (PCB). An anisotropic conductive film (ACF) is used to transmit electrical signals between the ceramic substrate and the PCB. To achieve optical coupling, optical fibers are butt-coupled with optical devices mounted in a cavity on the ceramic substrate. Alignment between the twelve optical fibers and the 12-channel optical device is achieved using guide pins fabricated in the ceramic substrate and guide holes fabricated in the optical connector.

Self-Alignment of Optical Devices With Fiber for Low-Cost Optical Interconnect Modules

We propose a novel self-alignment process of optical devices with optical fiber. A vertical-cavity surface-emitting laser (VCSEL) was automatically coupled with a multimode fiber (MMF) through the surface tension of a liquid adhesive within 1.5 s. Misalignment between the center of the VCSEL and the fiber was measured to be 15 mum, which is acceptable for coupling the VCSEL with the MMF. High-speed pulse modulation of the self-aligned VCSEL up to 5 Gb/s, as well as at 1 Gb/s, was demonstrated. The average optical output power was as high as -5.9 dBm at 1 Gb/s.

Ultraprecision Fabrication of Glass Ceramic Aspherical Mirrors by ELID-Grinding with a Nano-Level Positioning Hydrostatic Drive System

Glass and ceramic aspherical mirrors used as optical element s in a space astronomical observatory must be machined with very high profile accuracy and surfa ce smoothness. Precision grinding processes are very effective in fabrication of su ch profiles. In particular, with the ELID (Electrolytic In-Process Dressing) grinding method, it is possibl e to achieve ultraprecise and smooth surfaces of hard and brittle materials. To obtain the ultra smooth s urfaces, a final polishing process which requires a long processing time after the conventional grindi ng process is necessary. The ELID grinding method using an ultraprecision grinding machine tool with a nano-level hydrostatic guide will be very effective in reducing the time required for the finial polishing process. In this paper, a new ELID grinding system is introduced and the experimenta l r sults of fabricating a glass-ceramic paraboloidal mirror are presented and discussed. The profil accuracy of the fabricated glass-ceramic mirror was found within 0.54 m P-V.

Fabrication and optical characteristics of a hemi-paraboloidal solid immersion mirror and designing of an optical head with the mirror

A hemi-paraboloidal solid immersion mirror is successfully fabricated with the ELID (electrolytic in-process dressing) grinding technology and the spot size obtained was 150% of that for diffraction limited processes. Small sized optical head would be possible with the HP-SIM, which size is comparable to that of a magnetic head for HDDs.