Shinsuke Terada

Demonstration of high-bandwidth data transmission above 240 Gbps for optoelectronic module with low-loss and low-crosstalk polynorbornene waveguides

We developed a novel flexible optoelectronic (O/E) transceiver module designed for high-bandwidth and low loss data transmission for board level interconnects. In the O/E module, integrated circuits (ICs) and two 12 channel O/E devices including 850 nm vertical-cavity surface-emitting laser diodes (VCSELs) and photodiodes (PDs) were flip-chip assembled on flexible printed circuit (FPC). O/E modules and a sheet of 24-channel polynorbornene (PNB) waveguides were fabricated separately by using cost-effective and standard packaging processes. At the end of the O/E module fabrication process, the PNB waveguide sheet was integrated on completed FPCs with ICs and O/E devices using bonding sheets. Micro-mirrors formed in PNB waveguides were passively aligned toward the corresponding active areas of O/E devices respectively. The PNB waveguide sheet (120 mm long) was bi-directionally linked between O/E modules. We successfully demonstrated data transmission up to 16 Gbps/channel using an optical linked O/E transceiver module with low-loss and low-crosstalk PNB waveguides.

Low-Loss Optical Interposer with Recessed Vertical-Cavity Surface-Emitting Laser Diode and Photodiode Chips into Si Substrate

A new interposer with an optical interconnection called optical interposer has been proposed for a high-performance parallel processor system. The optical interposer is composed of polynorbornene (PNB) optical waveguides with 45° micromirrors and a Si substrate having chip-sized through-Si holes of 150 µm depth. The polymeric waveguides are formed on the Si substrate before forming the through-Si holes by deep reactive ion etching (DRIE). Vertical-cavity surface-emitting laser diode (VCSEL) and photodiode (PD) chips are placed onto the photolithographically defined hole patterns that are 15 µm larger than the size of the chips. In addition, the chips can be precisely aligned and recessed into the holes by passive alignment of self-assembly driven by the surface tension of a lead-free solder. We can fabricate the low-loss optical interposer with an insertion loss of below 0.2 dB measured at the waveguide length of 5 cm and a coupling loss of 0.5 dB measured with a 45° micromirror.

Impact of Data Transmission over 10 Gbps on High-Density and Low-Cost Optoelectronic Module with Polynorbornene Waveguides

We proposed a rigid/flex optoelectronic (O/E) module with 48-channel polymeric waveguides for short-distance board-level optical interconnection. A flexible O/E test module was fabricated in the following two steps by using standard packaging processes. First, two vertical cavity surface emitting laser diodes (VCSELs) and one VCSEL driver (VD) were flip-chip bonded to a completed flexible printed circuit board (PCB), and two photodiodes (PDs) and one transimpedance amplifier/limiting amplifier (TIA/LA) to another flexible PCB. Second, the two flexible PCBs were attached with a polynorbornene (PNB) sheet in which high-density PNB waveguides were formed by UV exposure. Active areas of VCSELs and PDs on the flexible PCBs were aligned to micromirrors of the waveguides with -6 µm offset toward the signal propagation direction. We successfully demonstrated data transmission over 10 Gbps and low inter-channel crosstalk of less than -20 dB was achieved in the flexible O/E test module with 120-mm-long and 62.5-µm-pitch waveguides.

High-bandwidth data transmission of new transceiver module through optical interconnection

This paper presents optical interconnection for module-to-module length for high-performance computing system. A new multi-chip transceiver module consisting of optical components, IC chips, flexible printed circuits (FPCs), and a sheet of optical polynorbornene (PNB) waveguides was fabricated by simple packaging processes. Waveguide sheet with micromirrors and the FPCs mounting of O/E devices were completed independently. After that, the waveguide sheet was aligned to optical devices on FPCs passively. Optical loss for waveguide including propagation and micromirror couplings was 3.30 dB. We successfully demonstrate high-bandwidth 100-Gbps (12.5 Gbps/ch × 8 channels) data transmission with the module, on which two 4-channel vertical-cavity surface emitting laser (VCSEL) arrays, one VCSEL driver (VD), two 4-channel PD arrays, and one transimpedance amplifier/limiting amplifier (TIA/LA) were mounted.

Improvement of polynorbornene waveguide based O/E module performance with microlens structure

The Optoelectronic (O/E) module with polymer waveguides is one of necessary items in order to realize optical interconnection technology. Generally, the optical coupling loss of O/E modules results from the gap between polymer waveguides and O/E devices mounted on electrical substrate. Reduction of the optical coupling loss is an important challenge because the coupling loss is contributory to increment of power consumption of O/E modules. In order to decrease the optical coupling loss, we propose polymer waveguides with lens structure for O/E module and its fabrication process. We report that optical loss was less than 3dB with lens structure.