For applications such as on-chip and intrachip optical communications, electrically pumped lasers with compact size, low power dissipation, and low-threshold operation are needed. Unfortunately, photonic-crystal (PC) nanocavity and microcavity lasers only offer ultralow nanowatt-range thresholds through optical pumping, because electrically pumped devices have proven challenging to fabricate. But researchers at Stanford University (Stanford, CA), Lawrence Berkeley National Laboratory (Berkeley, CA), and the University of California–Berkeley have succeeded in developing an electrically pumped, quantum-dot-based PC laser with a threshold-power dissipation of only 181 nA at 50 K—comparable to optically pumped PC lasers, and 1000 times smaller than the best conventional vertical-cavity surface-emitting lasers (VCSELs).
The team achieved this record threshold by developing a simple, flexible fabrication procedure that gives better control of current flow through the laser’s tiny cavity. A lateral p-i-n region is created in a PC lattice composed of a beryllium-doped p-type region, a silicon-doped n-type region, and a three-hole-defect gain region incorporating three layers of high-density indium arsenide (InAs) quantum dots. In this configuration, current flow is defined lithographically to flow only to the active region of the diode, making the device very efficient.
Contact Jelena Vuckovic at [email protected].
