Hidetoshi Numata

Dot pattern generation technique using molecular dynamics

We have developed a new technique for generating homogeneously distributed irregular dot patterns useful for optical devices and digital halftoning technologies. To introduce irregularity, we use elaborately designed sequences called low-discrepancy sequences instead of pseudorandom numbers. We also use a molecular-dynamics redistribution method to improve the distribution of dots. Our method can produce arbitrary density distributions in accordance with a given design. The generated patterns are free from visible roughness as well as any moiré patterns when superimposed on other regular patterns. We demonstrate that our method effectively improves luminance uniformity and eliminates moiré patterns when used for a backlight unit of a liquid-crystal display.

Assembly of mechanically compliant interfaces between optical fibers and nanophotonic chips

Silicon nanophotonics may bring disruptive advances to datacom, telecom, and high performance computing. However, the deployment of this technology is hampered by the difficulty of cost efficient optical inputs and outputs. To address this challenge, we have recently proposed a low-cost, mechanically compliant polymer interface between standard single mode fibers and nanophotonic waveguides. Our concept promises better mechanical reliability and better optical performance than existing technology. To manage the cost of assembly, we show here that self-alignment features can be effectively used to bridge the gap between the accuracy required by single-mode optics (1-2 um) and the capability of high-throughput microelectronic assembly equipment (~10 um). We describe the complaint interface, the assembly strategy, and the design of our re-alignment features. We demonstrate experimentally that misalignments at assembly as large as +/-10 um are re-aligned by our self-alignment structures to +/-1 to 2 um. Our approach enables existing microelectronics equipment to be used for singlemode optics assembly.

High-bandwidth, chip-based optical interconnects on waveguide-integrated SLC for optical off-chip I/O

As computing systems evolve for high performance with high power efficiency and exploit multi-core architecture, requirements for high-speed I/O are getting harder and could not be satisfied with optical interconnects. In addition to realize low power with optics by utilizing CMOS technology for high-sped driver circuits, chip-level packaging of optical integration are crucial to implement high-density optical channels, which are one of the requirements for the multi-core systems. Waveguide-integrated surface laminar circuit (SLC) have been developed for the chip-based, high-density optical interconnects. The power budget of optical link based on the chip-based optical interconnects are analyzed, since the budget affects the power dissipation of the link, and the fabrication process of the waveguides-integrated SLC is optimized to reduce the loss. This technology is then exploited into optical off-chip I/O for logic ICs, i.e. FPGA in this paper.

High-density optical interconnect exploiting build-up waveguide-on-SLC board

More optical channels have been implemented into computing systems as the system performance keeps increasing. Optical interconnects bring advantage of high data rate density, i.e. large bandwidth with small physical dimensions, as well as large bandwidth x distance product. High data rate density enables tight integration of many optical channels with electronic chips. One technique to implement such high density benefit is a printed circuit board (PCB) integrated with optical waveguides. In this paper, we will present an optical interconnect employing a waveguide- integrated surface laminar circuit (SLC) board. A build-up waveguide layer is formed on a SLC by laminating polymer films. Both optical and electronic chips are flip-chip mounted on the board. Optical signals are coupled with the waveguides by a 45-degree mirror formed on the waveguide. Electrical connections between the chips and the SLC circuits are provided by electrical vias through the waveguide layer. 10 Gbps operation has been demonstrated by a vertical-cavity surface-emitting laser (VCSEL) mounted on the waveguide-on-SLC board.

OE Device Integration for Optically Enabled MCM

We propose a new architecture of optical device integration on SLC carrier with capability of handling of the optical signals directly on MCM, or an optically enabled MCM, where VCSELs/PDs and the interface chips are placed closer to the main VLSI on a waveguide integrated SLC, while the optical connectors are at the periphery of the SLC carrier. This separated structure allows the highest number of optical channels per periphery length defined by the connector size, as well as the higher optical speed.

A novel dot‐pattern generation to improve luminance uniformity of LCD backlight

We report on a novel theoretical approach to generate irregular dot patterns, providing an integrated solution to difficulties peculiar to collimated -type backlight units. By applying this technology to a light guide and a diffuser film, the

A Novel Approach to Photonic Packaging Leveraging Existing High-Throughput Microelectronic Facilities

Silicon photonics leverages microelectronic fabrication facilities to achieve photonic circuits of unprecedented complexity and cost efficiency. This efficiency does not yet translate to optical packaging, however, which has not evolved substantially from legacy devices. To reach the potential of silicon photonics, we argue that disruptive advances in the packaging cost, scalability in the optical port count, and scalability in the manufacturing volume are required. To attain these, we establish a novel photonic packaging direction based on leveraging existing microelectronics packaging facilities. We demonstrate two approaches to fiber-to-chip interfacing and one to hybrid photonic integration involving direct flip-chip assembly of photonic dies. Self-alignment is used throughout to compensate for insufficient placement accuracy of high-throughput pick and place tools. We show a self-aligned peak transmission of -1.3 dB from standard cleaved fibers to chip and of -1.1 dB from chip to chip. The demonstrated approaches are meant to be universal by simultaneously allowing wide spectral bandwidth for coarse wavelength division multiplexing and large optical-port count.

Optical Interconnects for Servers

This paper looks briefly at server trends from an input–output (I/O) perspective. Based on these trends it is envisioned that high speed parallel optical interconnects attached directly next to the data source IC will be required within one to two generations. Examples of two projects, one fiber based and one polymer waveguide based, that move the field closer to that vision are described.

43.1: Color Filterless Liquid Crystal Display Illuminated with LEDs

We have prototyped a 13.3-inch diagonal color filterless LCD illuminated with LEDs. A new color directional backlight combined with a microlens attached liquid crystal cell plate shows the feasibility of a new power efficient LCD with better color and lead-free features.

Optical interconnect demonstrator with embedded waveguides and butt-coupled optoelectronic modules

Building blocks and experimental results of an optical card-backplane-card link with waveguides embedded into the boards and butt-coupled optoelectronic modules are presented. Important next steps for acceptance of the technology by system developers are listed.