12 February 2010


MOSEL project develops long-wavelength VCSELs for next generation high-speed communication systems

A team of researchers led by CEA -LETI of Grenoble, France have developed Long-wavelength VCSELs (Vertical-Cavity Surface-Emitting Lasers) for next generation high-speed communication systems, under the European project MOSEL, a three-year joint research program.

Along with lead organisation CEA -LETI, MOSEL 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.

According to the researchers, these performances pave the way to next generation devices and commercialization. Due to their intrinsic performances (power consumption, beam quality) and low cost potential, long-wavelength VCSELs provide a technological solution to an economical problem, says the consortium.

Working together, the six consortium partners focused on different areas of development:

  • DTU Fotonik researched VCSELs with nano- and micro-structures, aiming at high single-mode output power. It found that nano- and micro- structures can feasibly suppress higher order modes or shape the optical mode profile to match well with a gain profile, promising three times enhanced strength of single-mode operation. A hybrid VCSEL structure incorporating a III-V gain region and a silicon photonic crystal mirror was suggested for silicon photonic applications.
  • Alight Technologies aims to supply long-wavelength VCSELs for tele- and data-communication applications. As a part of the project, the firm refined the photonic crystal structuring of its long-wavelength GaInNAs/GaAs VCSELs. Furthermore, Alight worked on extending the high-speed operation of its long-wavelength VCSELs and recently demonstrated error-free 10GBASE-LR operation up to 100°C.
  • EPFL and BeamExpress worked together to improve the performance of 1310nm-waveband VCSELs and reach commercialization based on their proprietary InP-GaAs wafer-fusion technology. The fabricated devices use 2” wafer technology, incorporate patterned tunnel junctions and other intra-cavity structuring elements for efficient carrier and photon confinements, and show 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. This wafer-fusion technology was used to produce VCSELs with similar high performance in the entire 1200-1600nm wavelength range. BeamExpress is working with a manufacturing partner in Europe to commercialize long-wavelength VCSELs. First samples were available in Q4/2009.
  • KTH has used a novel re-growth technology with mode-selective elements for high-power single-mode emission. The technology is entirely based on standard materials and processing methods, and in principal allows for direct implementation in a standard processing line for short-wavelength VCSELs. It demonstrates significant potential for improved efficiency, manufacturability and reliability.
  • CEA-Leti focused on the development of a new VCSEL design using a recently suggested high-reflectivity-mirror concept based on sub-wavelength grating mirrors. The first results show sub-milliamp threshold current, a linearly polarized emission as well as single-mode maximum output power at 980nm of more than 4 mW (1mw) at room temperature (70°C). A high-index contrast between the photonic crystal membrane and the underlying material is obtained by selective oxidation of a high aluminium-content layer. CEA-Leti says that the results build a bridge between a standard VCSEL and a hybrid laser, making them of potential use for the realization of silicon photonics.

See related items:

Alight and ULM partner on volume VCSEL production

BeamExpress raises $1.3m in first-round funding

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