Vertical Cavity Laser Diodes and Arrays for Efficient Fiber Coupling and High Speed Data Transmission in Optical Interconnects

Abstract

Vertical cavity laser diodes (VCSELs) form a new class of semiconductor lasers extremely prospective for a wide range of applications, e.g. in parallel fiber links, optical interconnects and cross connects, bar code scanners, compact optical disk systems and laser printers. Parallel fiber busses using VCSEL transmitters have just entered the market. Compared to conventional edge emitting laser diodes VCSELs have distinct advantages like low divergence, astigmatic-free output beams for efficient fiber coupling or dynamic single-mode emission up to 40 Gbit/s data rates under direct modulation. Two-dimensional independently addressable laser diode arrays are easily produced and may be applied for display or monitoring purposes or coupling to fiber bundles. Like light emitting diodes VCSELs are manufactured on wafer scale and testing is also performed directly on-wafer. This is in contrast to edge emitting lasers where cleaving is required and testing is performed after dicing and facet coating which leads to comparatively high fabrication costs. Moreover, mounting and packaging requirements are expected to be much less for VCSELs than for edge emitters.