Optical upconverter with integrated heterojunction phototransistor and light-emitting diode - art. no. 073501

We report an optical upconversion device that converts input 1.5 mu m light to output 0.87 mu m light with a built-in gain mechanism. The device consists of an InGaAs/InP heterojunction phototransistor (HPT) integrated with a GaAs/AlGaAs light-emitting diode (LED) by wafer fusion process. Incoming 1.5 mu m optical radiation is absorbed by the HPT, generating an amplified photocurrent. The resultant photocurrent drives the LED that emits at 0.87 mu m, which could be detected by a conventional silicon charge-coupled device. Upconversion is demonstrated at room temperature with a gain of 20 from the HPT and an overall external upconversion efficiency of 0.07 W/W.