Recent developments in the area of vertical cavity surface emitting lasers

Vertical Cavity Surface Emitting Lasers (VCSELs) show potential for use as low cost sources for optical communication. The structure is compatible with fabrication of 2 dimensional arrays, as no cleaved facets are needed for mirror function. In addition, the intrinsic single mode operation of the devices due to the short cavity leads to very high fabrication yield. Very fast progress has been achieved in the recent years for 0.85 - 0.98 mu m VCSELs fabrication. VCSEL arrays are therefore used in parallel optical interconnection systems; these systems are presently available on the public market. Bit rate as well as transmission length are however limited mainly by the multimode fiber used at this wavelength. In order to upgrade such systems beyond Gbit/s operation over several kilometres, important efforts are devoted to the development of 1.3 - 1.55 mu m VCSELs today. Starting with a simple test structure for the optimisation of optical (mirror), thermal (material) and electrical properties, we have proposed and demonstrated an original structure emitting at 1.3 mu m. CW operation is observed up to -15 degrees C. Characterisation of the devices are detailed as well as the way to increase their performances.