A 200MHz 300ps 0.5pJ/ns optical pulse generator array in 0.35μm CMOS

Short optical pulses are required for diagnostic techniques in life sciences such as fluorescence lifetime imaging, which can be used for quantitative detection of ion concentrations, oxygen and fluorescence resonance energy transfer (FRET) [1]. Conventionally, such pulses are produced by lasers and laser diodes with optical pulse widths in the femto-second or 10's of picosecond range with milliwatt optical power levels. However, the cost and physical size of these optical sources and associated electronics have prevented the emergence of fully-miniaturised optical lab-on-chip and biosensors although much progress has been made on integrated fluorescence lifetime detector arrays [2], [3]. We present an 8x8, 200μm-pitch driver array based on standard 0.35μm CMOS, bump-bonded to AlInGaN micro-LEDs. The array is capable of producing sub-nanosecond pulses at wavelengths from 370-450nm compatible with common organic fluorophores and multiplexed micro-array formats [4].