Long-wavelength VCSELs: Green solution to high-speed communication

GRENOBLE, FRANCE: Long-wavelength VCSELs (Vertical-Cavity Surface-Emitting Lasers) for the next generation of high-speed communication systems have been developed in the European project MOSEL, a three-year joint research program lead by CEA-Leti.

The research on long-wavelength VCSELs is aimed at finding an efficient and reliable technological answer to the ever-growing demands for bandwidth in telecommunication networks. Moreover, VCSEL technology offers low power consumption (from five to 10 times less than the conventional edge-emitting lasers) and can be manufactured in volume at low cost.

During the three years of the project, the six partners have worked together to push long-wavelength VCSEL technology from lab to industry. The MOSEL project was lead by CEA-Leti (France) and included three academic partners: DTU Fotonik (Denmark), EPFL (Switzerland), and KTH (Sweden), and two industrial partners: Alight Technologies (Denmark) and BeamExpress (Switzerland).

The project demonstrated error-free 10GBASE-LR operation up to 100 °C, concurrently with record performance: single-mode (>30dB SMSR) power of >1mW up to 100°C (>2mW at room temperature) and 10Gbps modulation and transmission over 10-km single mode fiber with BER <10–11 up to 100°C with <1-dB power penalty.

These performances allow industrial partners to address different previously established standards and pursue commercialization of the results. At the same time, the academic partners have demonstrated different proofs of innovative concepts, preparing the basis for the next device generation.

The ever-growing demands for bandwidth in telecommunication networks, mainly caused by the unprecedented growth in data traffic in local and access networks, necessitate the development of new, low-cost, high-speed optical links in the 1–100 Gbps range.

In contrast to the earlier evolution of optical fiber networks, the needs for high-bandwidth transmission have shifted from the high-capacity links (such as intercontinental and intercity) towards the network environment of the end users.

This development puts the emphasis on low-cost, intelligent and scalable networks that can be deployed throughout the entire network hierarchy, ranging from metropolitan and local area networks (LANs) to access networks such as fiber-to-the-home (FTTH) and passive optical networks (PONs).

Due to their intrinsic performances (power consumption, beam quality) and low cost potential (mass production already proven in the case of optical mice), long- wavelength VCSELs provide a technological solution to an economical problem. Indeed, employing novel concepts for mode control and current injection has enabled the consortium to demonstrate device performances similar to or, in some cases, surpassing those of conventional edge-emitting lasers.