Shigeo Tanahashi

Three dimensional optical interconnect on organic circuit board

We propose high speed optical interconnection which is three dimensional optical lanes using polymer materials fabricated on an organic circuit board with metal lines and pads. These optical lanes transmit optical signals not only on a plane surface but into the other side of a circuit board. It has following three particular portions; (1) curved parallel optical waveguide; (2) 45 degree reflection mirror; (3) optical via hole. Four channel three dimensional optical lanes with current electrical lines and pads are newly developed on the organic circuit board named CPCoretrade. We characterize the optical lanes by transmission loss and passed through eye diagram, and optical signal transmission is confirmed. Then optical signal transmission up to 3Gbps/channel are demonstrated with 850nm VCSEL flip-attached on the circuit board with active and passive electronic devices and components as driving circuit

A siloxane polymer lightwave circuit on ceramic substrate applicable to ultrafast optoelectronic multi-chip-modules

Technique for integrating optical waveguide circuits on electrical circuits is developed toward the application to opto-electronic multi-chip modules (O/E-MCM), which enables one to handle ultrafast lightwave pulses and electrical signals on a common circuit board. We use ceramic material as the substrate of O/E-MCM having a multi-layer structure. A siloxane polymer is utilized to form low loss optical waveguides on ceramic substrates by low temperature processes. The waveguide has shown high transparency around 1310 nm. The group velocity dispersion has been measured and shown to become almost zero at wavelength of 1310 nm and about 0.4 fs/cm nm at 1550 nm. An optical circuit has been formed on simple electrical circuit consisting of a thermometer film resistance layer. A Mach–Zehnder interferometer optical switch exhibiting the waveguide extinction ratio of 30 dB, control power of 5 mW, and switching speed of 6 ms has been demonstrated. Thermal management characteristics also have been demonstrated successfully. This single-mode optical waveguide can thus be formed readily on ceramic substrates involving electrical circuit layers; this result confirms its applicability to O/E-MCM.

Superconductor Wiring in Multichip Module for Josephson LSI Circuits

Nb/polyimide stacked layers on a multilayer ceramic substrate makes it possible to fabricate superconducting off-chip wiring for control signal lines. This superconducting multichip module (SuperMCM) also provides matching circuits for the clock signal and DC bias circuits beneath the superconducting transmission lines. The first prototype SuperMCM in the world successfully made,which has been designed to drive Josephson LSI chips at the highest clock frequency of 1.2 GHz.

Three-dimensional optical lines fabricated onto substrate for on-board interconnection

Optical lines using polymer materials fabricated on an organic substrate with metal lines and pads are proposed to realize fully optical interconnections among high performance LSIs. This optical line enable transmit high speed optical signals not only on a plane surface but to vertical direction. It has following four particular portions; (1) Curved parallel optical waveguide; (2) 45 degree reflection mirror; (3) Optical via hole with coaxial structure; (4) Optical joint between package and board. The optical line characterized by transmission loss and passed through eye diagram, and good optical signal transmission is confirmed to really use for optical interconnection between LSIs. Then on-board optical signal transmission is demonstrated by that VCSEL and PIN-PD are assembled using flip-chip technology on a circuit board with other electric devices of driving circuit, and also package-to-board optical joint are demonstrated by passing through solder reflow process.

New single-mode optical waveguide on ceramic substrate utilizing siloxane polymer

A new single-mode optical waveguide on a ceramic substrate has been developed to obtain opto-electronic multichip modules for use of high operating frequencies. Propagation loss of the single-mode optical waveguide formed on ceramic substrate is 0.14dB/cm for 1.3 micrometers wavelength.It is fabricated utilizing a siloxane polymer. The film of siloxane polymer can cut-off surface roughness of ceramic substrate. So the optical waveguide on ceramic substrate utilizing the siloxane polymer has fine optical characteristics.

New premolded package with optical fiber guide pipe

A new pre-molded organic package with optical fiber guide pipe has been developed to meet the demand of significant package cost reduction in subscriber systems. The new pre- molded package is composed of a new organic materia which has high anti-moisture reliability. The new pre-molded package has not degraded after reliability test including thermal shock, temperature cycling and PCT of 0 to 100C/500 cycle, -40 to 84 C/500 cycle and 121C/2atm, respectively. The new developed pre-molded package with the guide pipe can be used in the subscriber systems with low- cost effect and high reliability.

Single-mode optical waveguide using siloxane polymer on Cu-polyimide substrate

A new single mode optical waveguide has been developed to obtain optoelectronic multichip modules. It is fabricated using siloxane polymer and thin film process technology onto a copper polyimide ceramic substrate. The siloxane polymer refractive index is 1.451, very similar to that of SiO/sub 2/. It is revealed that titanium doped siloxane polymer has refractive index of 1.4537 to 1.5949 (at 632.8 nm wavelength) which can be controlled by the TiO/sub 2/ content. The siloxane polymer which contains 2.0 wt% of TiO/sub 2/ has refractive index of 1.4437 at 1550 nm wavelength. Therefore, the siloxane polymer and the TiO/sub 2/ doped siloxane polymer can be used for cladding and core layers respectively, enabling a single mode waveguide. The core size is designed to be 4-8 /spl mu/m wide by 7.0 /spl mu/m thick to obtain a single mode optical waveguide at /spl Delta/n=0.0022.

Packaging technology of OptoBGA for 2.4 Gb/s

The significantly increasing transmission capacity in the subscriber system are accelerating demands for higher data transmission speed, low cost, and system miniaturization in the millennium approaches. The key solution for the demands, smaller, lower cost, and high performance package, is surface technology. OptoBGA package has been developed to meet this challenge, a surface mountable type optical package that is designed for high frequency transmission speeds. OptoBGA package has a BGA structure to bring forth effectively size and cost reduction for the packaging. OptoBGA consists of ceramic material, a robust material, which has many advantages such as design flexibility with fine design rule, ease of process technology, high performance, and high reliability. The design of OptoBGA was made possible by improvement in the physical structure. The results of this research produced an OptoBGA with a return loss of about -20dB at 10GHz. Furthermore, reliability test evaluations have been conducted to demonstrate that the OptoBGA can withstand harsh environments.

High reliability pre-mold package with optical fiber guide pipe

A pre-mold package with optical fiber guide pipe has been developed to supply the low cost package for the access network systems market. This paper describes the PD module utilizing the premold package which has a very low variation of dark current after the reliability test. It is very close to that of TO-CAN type PD. In this paper, we propose the premold package to meet the market requirements offering low cost and high reliability solution.

Small Strip Line Module for Superconducting Filter

We have developed a new strip line filter module with small size and high heat dissipation capacity. The new filter module is composed of substrates for a filter and ground planes, and the size is much smaller than the conventional height of RF housing and has a thickness of the order of a few substrates. For the evaluation of transmission characteristics of the strip line module, simple strip line modules containing no filter and two alumina substrates were used. The minimum insertion loss of the modules is of the order of 0.1dB(input 44dBm) at temperatures of 50K–77K, and their properties are sufficient for actual systems.