Yoshitsugu Wakazono

High-density and Low-cost 10-Gbps x 12ch Optical Modules for High-end Optical Interconnect Applications

We demonstrated 10-Gbps/ch operation of high-density and low-cost 12-channel optical modules. High-Δ bent fiber connector is butt-coupled with OE-substrate. Fabricated module is as small as 10 mm x 10 mm footprint with thickness of 6 mm.

Low-Cost and High-Density 10Gbps/ch Optical Parallel Link Module for Multi-Terabit Router Application

We demonstrated 10-Gbps operation of low-cost and high-density optical parallel link module for multi-terabit routers. Four-channel high-¿ optical fibers are directly coupled with optical devices without micro-lenses. Easy assembly was realized by executing visual alignment.

Vertically Pluggable and Compact 10-Gb/s

We have developed a vertically pluggable and compact 12-channel optical module for intercabinet and intracabinet optical interconnections. Error-free and over 10 Gb/s operation of the optical module with an electrical and optical connector have been demonstrated. The module is designed to be 10 mm in width, 10 mm in length, and 6 mm in thickness so that it can be placed around the central processing units. This compact optical module can be mounted on the inner board area. Further, this module is vertically pluggable in the z-direction, i.e., in a direction that is perpendicular to the board. Because of the vertical pluggability, the optical modules can be repaired much more easily. The optical connector used in the low-height module has 12 fine-drawn graded-index multimode fibers (MMFs). These fibers have a high relative refractive index difference (Delta) and are bent with a 2 mm radius of curvature. The electrical connector consists of an anisotropic conductive film that is sandwiched between an alumina substrate and a printed circuit board with a clamp spring. We have used the alumina substrate to mount the optical device and the driver integrated circuit, because of its high thermal conductivity. In order to reduce cost, we have not used either a microlens or a metal-coated mirror in the optical module. Furthermore, passive alignment between the MMFs and the optical device has been achieved using guide pins assembled in the alumina substrate.

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We propose a self-alignment process of an optical device with an optical multimode fiber (MMF) and a novel optical subassembly using a pre-self-aligned device. In order to form the pre-self-aligned device, the optical device such as a vertical-cavity surface-emitting laser (VCSEL) is aligned with the MMF using the surface tension of a transparent liquid adhesive. The optical subassembly we have developed is provided with a simple structure consisting of the pre-self-aligned VCSEL and an interposer board to be mounted on a printed circuit board (PCB). Details of the low-cost self-alignment technology and the optical subassembly are reported. Alignment accuracy of average 13 ¿m is achieved and coupling efficiency of the self-aligned VCSEL to the MMF is determined to be maximum 35%. 1-Gb/s optical signal transmission using the optical subassembly is also demonstrated. This self-alignment technology and the fabricated optical subassembly are effective in achieving low-cost optical modules for optical interconnect systems from commodities to high-end applications.

12-Channel Optical Modules With Anisotropic Conductive Film for Over 100-Gb/s Optical Interconnect Systems

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.

Low-Cost Optical Subassembly Using VCSEL Pre-Self-Aligned With Optical Fiber for Optical Interconnect Applications

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.

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

We analyzed the coupling efficiency between VCSEL and a optical component with high-delta fibers experimentally. The high-delta fiber was able to relax restrictions in alignment between fibers and VCSEL because of the increase of NA.

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

New serial data transmission standards for cameras and displays in mobile devices are demanding low power multi-gigabit high speed serial links which must operate in noisy RF environments. [1] To meet these requirements a hybrid optical/electrical interconnect link is proposed. By combining a traditional flexible electrical interconnect with an advanced low power optical interconnect it is possible to meet the demands of this future market. The two key developments discussed in this paper are: the electrical/optical switching system, which is the basis for the hybrid link, and the all planar assembly process, featuring an edge emitting laser diode, edge receiving photodiode and a flexible polymer waveguide.