US researchers built a gallium nitride micro-LED for text-based LED data transfer inside data centres, finding a 5-micrometre size best balances speed and power.
A US team set a quantum-well micro-LED record: 2.75 GHz optical modulation bandwidth on 25 milliwatts.
The gallium nitride device was built by researchers at the University of Illinois Urbana-Champaign and the University of Notre Dame.
A 5-micrometre diameter outperformed both larger and smaller sizes in the tested range from 100 down to 2 micrometres.
About 90% of data-centre traffic moves less than 10 metres between racks, a range where lasers today use heavy power and cooling.
Arrays of these emitters could carry many independent streams on one compact chip for hyperscale operators.