Integration of microlensed LED and double heterojunction bipolar transistors for transmitter OEIC

An optoelectronic integrated circuit (OEIC) consisting of a highly focusing AlGaAs microlensed LED and a double heterojunction bipolar transistor (DHBT) has been fabricated. A 30 μm radius microlens was used to focus IR radiation into a beam-spot smaller than 3 μm. A microlensed LED focused its output light within a full width at half maximum (FWHM) of 17° in the far field pattern. An integrated microlensed LED radiated ~35 mW of maximum light output with a driving current of 120 mA, and its driving DHBT with a 10×15 μm² emitter showed a DC current gain of β=20