A 25.78-Gbit/s × 4-ch Active Optical Cable with Ultra-Compact Form Factor for High-Density Optical Interconnects

Naohiro Kohmu,Hideo Arimoto,Norio Chujo,Toshiaki Takai

doi:10.3390/app8010137

Naohiro Kohmu, Hideo Arimoto + Show 2 more

Open Access

https://doi.org/10.3390/app8010137

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Journal: Applied sciences	Publication Date: Jan 18, 2018
Citations: 7	License type: CC BY 4.0

Affiliation: Hitachi (Japan), Japan Lifeline (Japan)

Abstract

A 25.78-Gbit/s × 4-ch active optical cable (AOC) with an ultra-compact form factor is proposed. The size of the proposed AOC is 5.2 cm3, which is 55% smaller than the standard form factor of Quad Small Form-factor Pluggable (QSFP28), and 45% smaller than that of Micro Quad Small Form-factor Pluggable (μQSFP). As a result of utilizing a high-efficiency heat-dissipation structure and optimizing signal transmission lines and ground vias, the proposed AOC achieves high-heat dissipation and low-crosstalk characteristics. Furthermore, the proposed AOC demonstrated 25.78-Gbit/s error-free optical transmission over a 100-m Optical Multimode 3 (OM3) multimode fiber under all-channels (4-ch) operation and case temperature (Tc) of 70 °C.

Highlights

With the drastic increase of data traffic in datacenters (DCs) and the evolution of high-performance computing (HPC), high-speed (>25 Gbit/s) data communication are required
We developed a 25.78-Gbit/s × 4-ch active optical cable (AOC) integrated with a newly ultra-compact form factor
The temperature of the vertical cavity surface emitting laser (VCSEL) of the fabricated AOC was measured by a thermocouple in a thermostatic chamber with the temperature was controlled so that the case temperature becomes constant at Tc = 70 ◦ C

Summary

Introduction

With the drastic increase of data traffic in datacenters (DCs) and the evolution of high-performance computing (HPC), high-speed (>25 Gbit/s) data communication are required. In the case of conventional electrical interconnects, high-speed and long distance (>10 m) transmission is challenging due to large transmission loss [1]. Optical interconnects have the advantage that high-speed signals can be transmitted further than in an electrical one with low propagation loss. For high-density signal transmission, it has become necessary to increase the total input/output (I/O) capacity. We previously proposed a 25.78-Gbit/s × 12-ch AOC in the same size as the form factor of QSFP28 [7]. To meet system requirements, 4-ch and 1-ch AOCs are required

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