On-chip activation of superlattice detectors via light coupled out laterally from optical fibres

A novel scheme for tapping of signals carried in optical fibres is demonstrated. Lateral holes through the fibre cladding, formed by lithography and chemical etching or laser machining, are filled with a high-index plug to allow access to the guiding region. The fibre is positioned in a groove in the active semiconductor wafer, and the holes are aligned with a row of mesa-type superlattice avalanche photodiodes which detect the optical signal.