Masato Shishikura

A High-Coupling-Efficiency Multilayer Optical Printed Wiring Board with a Cube-Core Structure for High-Density Optical Interconnections

A multilayer optical printed wiring board with a cube-core structure was developed for high-density optical interconnections. A fabricated multilayer optical printed wiring board with this cube-core structure has optical-coupling efficiency 2.7 dB higher than one without this structure. A fabricated optical interconnection model successfully demonstrated 10-Gbit/s/channel operation. These results show that the advantage of this cube-core structure is that it provides high optical-coupling efficiency in a high-density multilayer optical printed wiring board.

25-Gbps receiver for 100-Gbps ethernet employing cost-effective small coaxial package

We developed a 25-Gbps receiver employing a small, cost effective coaxial package and flexible printed circuits. Our fabrication method for reducing electrical resonance and loss was effectively applied. The fabricated receiver had a 24-GHz 3-dB bandwidth and was successfully operated at 25 Gbps.

10 Gbit/s per channel parallel optical transmitter and receiver modules for high-capacity interconnects

We used a channel-pitch conversion structure to suppress inter-channel crosstalk in 4-channel x 10-Gbit/s parallel optical transmitter and receiver modules for use in highcapacity optical interconnection. Error-fkee transmission with the total throughput of 40 GbiUs over 600 m was successfully demonstrated. 1. Introduction The rapidly increasing volume of data tra& requires the use of cost-effective high-capacity optical interconnection between routers and fiber-transmission equipment in a same building. A parallel optical link is one of the best solutions for such very-short-reach (VSR) applications because of its simple and cost-effective configuration. Many vendors have been developing various configurations for parallel optical links made by ribbon fiber, such as 4- and 12-channel x 2.53.125-GbiUs transmitters and receivers (with a total throughput of 12.5-30 Gbitls) [I, 21. In the near future, parallel optical links with a total throughput of 40 GbiUs and beyond will be needed. One way to achieve veIy highcapacity transmission is to use parallel optical interconnection with a transmission speed of 10 GbiUs per channel [3]. A 4channel configuration [4] with 10-GbiUs channels has enabled all-duplex transmission with a simple single 8-channel ribbon-fiber cable. However, strong inter-channel crosstalk at the high per-channel rate makes multi-channel operation at this rate impracticable. To suppress the inter-channel crosstalk in a parallel architecture, we have developed a channel-pitch conversion structure based on a polymer planar lightwave circuit (PLC) platform, and demonstrated 4-channel x 10-GbiUs parallel transmitter and receiver modules [5-71. In this paper. we describe the characteristics of the fabricated transmitter and receiver modules. We also report on our successfid demonstration of error-free 10GbiUskhannel transmission with the total throughput of 40 Gbitk over 600 m (VSR) and an optical power budget of more than 6 dB.

Highly Reliable Operation of InGaAlAs Waveguide Photodiodes for Optical Access Network Systems

Reliability of InGaAlAs mesa waveguide photodiodes suitable for low-cost modules applied to access network systems is investigated. Stable operation for 9600 hours has been confirmed so far in the bias-temperature accelerated aging test. Median lifetime at a field service temperature of 85°C is estimated to be over 100 years by using the measured activation energy of 0.48 eV. Change in dark current during aging is explained by the hole accumulation at the interface between a crystal surface and a passivation film. The waveguide photodiode is confirmed to be highly reliable for access network applications.

Highly efficient lens-less coupling of high-speed waveguide photodiode to SMF and its application to an extremely thin surface-mountable 10-Gbps receiver module

We demonstrate a high-speed waveguide photo-diode that has high responsivity when butt-coupled to a flat-ended single-mode fiber. An extremely thin lens-less surface-mountable 10-Gbps receiver module with this photodiode installed has a high responsivity (0.97 A/W) and high sensitivity (-18.8 dBm).

A symmetric double-core InGaAlAs waveguide photodiode for hybrid integration on optical platforms

A symmetric InGaAlAs waveguide photodiode for low cost modules is investigated. A high responsivity of 0.95 A/W and a low dark current after 1900 hours aging of 300 pA are demonstrated. In this paper, we optimize the symmetric doublecore structure for higher responsivity while maintaining a wide coupling tolerance at a low operating voltage. We also describe the use of a surface passivation technique to achieve low dark current operation over a wide temperature range and after aging at 200 C.

1.3-

A four-channel times10-Gb/s parallel optical transceiver for high-capacity very-short-reach applications was developed. The transceiver module was fabricated with low-cost components such as polymer planar lightwave circuit (PLC) platforms and 1.3-mum Fabry-Perot laser diodes (FPLDs). The polymer PLC platform enables the FPLDs or waveguide photodiodes (WGPDs) to be butt-coupled to the polymer waveguide by low-cost passive alignment. Using 1.3-mum FPLDs and single-mode fibers (SMFs) achieves reliable transmission over 600 m. Widening the spacing between the waveguides up to 1 mm suppressed the interchannel crosstalk to below -39 dB. The fabricated transceiver was operated at 10 Gb/s per channel and it successfully demonstrated 600-m error-free transmission. The sensitivity of each channel was better than -14 dBm with an interchannel-crosstalk penalty of less than 0.7 dB

mu

A 4-channel/spl times/10-Gbit/s parallel LD module for next-generation high-capacity optical interconnects was developed. To suppress the inter-channel crosstalk, a PPLC platform with a channel-pitch conversion function was also developed. Four un-cooled 1.3-/spl mu/m InGaAlAs FP-LDs were mounted on separated electrodes of the PPLC platform by passive alignment; thus, the module is compact and low cost. Crosstalk is as low as -40 dB. The module has a total throughput of 40 Gbit/s over 300-m transmission without suffering any degradation caused by inter-channel crosstalk. Our proposed 4-channel/spl times/10 Gbit/s parallel LD module can be applied to next-generation high-capacity optical interconnects.

m Four-Channel

4 ch × 25.8 Gbit/s WDM transmission over 40 km single mode fiber was demonstrated. Minimum receiver sensitivity each lane after 40 km transmission was less than −26.0 dBm, proving the transceiver will meet IEEE 100GBASE-ER4 specifications.

,times,

We used highly refractive silicon etalons to develop a tunable dispersion compensator with plusmn250-ps/nm tunable range and low <2.3-dB loss (2.1-dB improvement). We demonstrated 40-Gbps-NRZ transmissions with 1000-ps/nm tunable range in a double-pass configuration.