Monomode Surface Emitting Lasers

Informations projet

MOSEL

N° de convention de subvention: 035183

Projet clôturé

Date de début 1 Juin 2006

Date de fin 31 Mai 2009

Financé au titre de

• Information Society Technologies: thematic priority under the specific programme "Integrating and strengthening the European research area" (2002-2006).

Coût total € 3 669 105,00

Contribution de l’UE € 2 391 345,00

Coordonné par

COMMISSARIAT A L' ENERGIE ATOMIQUE
France

Résultats exploitables

Single mode performance of Vertical Cavity Surface Emitting Lasers (VCSELs)

The main goal of the project is to achieve improved single mode performance of Vertical Cavity Surface Emitting Lasers (VCSELs) using microscale and nanoscale patterning. Novel device designs will allow: - Increased size (and thereby power) of the fundamental transverse mode - Maintained transverse single mode performance over larger current ranges - Improved modulation speed - Controled beam polarisation over large temperature range under modulation. Low risk route Alight has optimised their VCSELs to operate at 10 Gbps up to 100 degrees centigrade with specifications in compliance with the goal of MOSEL and 10 GbE-LR standard. This was achieved by optimisation of the epitaxial structure and the physical layout of the VCSEL structure. Main achievement is an improvement of active quantum well structure increasing the quantum efficiency of the devices. The devices are similar in layout as the lower speed devices, which ensure rapid transfer to the foundry partner. First results on lifetime testing show very promising results exceeding our expectations from earlier generations of epitaxial material. Alight is now pursuing commercialisation of these results and expect to start limited sampling of devices in the fourth quarter of 2009. EPFL and BeamExpress demonstrated transmission experiment with VCSELs within MOSEL specifications with additional limitation on driving current imposed by application. The devices are fabricated using 2'' wafer technology, incorporate patterned tunnel junctions and other intra-cavity structuring elements for efficient carrier and photon confinements. The wafer fusion technology is employed for producing VCSELs with similarly high-performance in the entire 1200 - 1600 nm wavelength range. Record-high single-mode operation of 8 mW was demonstrated for 1550 nm waveband, which is the highest value of single-mode power ever demonstrated by a VCSEL. High risk route A new analysis method to measure various losses in VCSELs with nano or micro-structures was developed at DTU Fotonik. Singlemode mechanism in photonic crystal (PhC) VCSELs: It was revealed by using the new analysis method that the single mode mechanism in PhC VCSELs schematically shown in is attributed to the three times higher scattering loss of higher order modes due to the PhC air holes. Four solutions to polarisation instability problem: It was also shown that employing surface grating, surface sub-wavelength grating, intracavity sub-wavelength grating, or surface Au/C nanowires efficiently solves the polarisation instability problem of the tunnelling junction (TJ) VCSELs. Simulation results of the surface grating and surface Au/C nanowire cases were compared with experimental measurements, showing good agreements. Optimal parameter range for each structure has been suggested. Revision of design with experimental feedback: Long wavelength high-index-contrast sub-wavelength grating (HCG) VCSEL designs were revised with experimental feedback from CEA-LETI. Suspicious reasons for the experimentally observed non-lasing of the first design were corrected. HCG TJ VCSEL: A new long wavelength VCSEL structure employing a HCG and TJ was suggested. Two times stronger strength of single mode operation than a state-of-the-art single mode VCSEL structure was achieved. This is attributed to the synergy gained by combining the selective pumping in TJ VCSEL structure and the moderate mode selection by the HCG. Patent application: A hybrid silicon grating-mirror vertical-cavity laser (VCL) design for silicon photonics applications was applied for EU and US patents. In this design, the grating (or PhC) layer formed in the upper silicon layer of a SOI wafer functions both as a bottom mirror and as a coupler to a normal waveguide. MEMS tunable grating-mirror VCSEL with an 80 nm-tuning range (COM): In this design, the top HCG mirror layer is actuated by electrostatic or piezoelectric force. By extending the optical cavity, 80 nm-tuning range could be achieved while holding single-fundamental-mode operation. So far, 2.5 nm-tuning range has been experimentally reported by UC Berkley group.