Two dimensional (2D) arrays of phased locked lasers are of significant importance for the implementation of high power semiconductor lasers, 2D coherent sources for optical computing and interconnects and 2D beam switching and stirring. Recent progress in design and in growth and fabrication techniques has led to the demonstration of low threshold, efficient vertical cavity surface emitting lasers (VC-SEL)1, which enables the integration of large VC-SEL arrays. However, efficient phase locking of these lasers has not been demonstrated yet. Here we present phase locking of VC-SEL arrays by coupling of their cavity modes. These coupled modes are generated by laterally patterning the reflectivity of the back laser mirror. We obtain very efficient phase locking of the laser fields in specific coherent supermodes. These phase locked arrays exhibit significantly improved spatial coherence compared to broad area (BA) VC-SELs of the same size, which usually operate in an incoherent filamentary mode2. This is accomplished with fairly large interlaser distances (several micrometers) using a simple planarity preserving process and with minor increase in the threshold current compared to a BA VC-SEL of the same size.
© 1990 Optical Society of AmericaPDF Article