Direct backside connection of optical fibers to GaAs detectors

Photodetectors fabricated in GaAs have been vertically coupled to optical fibers using a cavity anisotropically etched in the backside of the GaAs substrate. The detector used was a Schottky photodiode amplified by an integrated MESFET. The cavity was etched from the backside using reactive ion etching (RIE). AlGaAs epitaxially grown on the substrate was used as an etch stop layer. A tapered optical fiber inserted in the backside cavity is accurately aligned to the detector and is mechanically stable. The vertical coupling approach is real-estate efficient and is particularly well suited for spatially parallel optical computing. © 1988 SPIE.