COHERENCE OF VCSELS FOR HOLOGRAPHIC INTERCONNECTS

Temporal and spatial coherence measurements were conducted on the emis sion from AlGaAs-GaAs vertical-cavity surface-emitting lasers (VCSEL's ), Results of both CW and pulsed conditions from devices of 8- and 15- mu m diameter are reported, Coherence length of 0.6 mm for multi-mode and similar to 75 cm for single-mode were obtained, Thermal chirp redu ces the single-mode coherence to 16 mm for 5 us pulses, For holograms smaller than 0.6 mm in size the density of information that can be rea d by the VCSEL's is diffraction-limited by the size of the holographic element.