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An Ultimately Low-Threshold Semiconductor Laser with Separate Quantum Confinements of Single Field Mode and Single Electron-Hole Pair

A novel semiconductor surface-emitting laser structure is proposed. All spontaneous emission is coupled into a single lasing mode by means of a quantum microcavity, and discrete electron-hole pair emission is made free of absorption by means of a dc-biased quantum dot. The quantum microcavity modifies the angle distribution of a vacuum field fluctuation that is a source of spontaneous emission. The dc-biased quantum dot separates the emission and absorption lines by image-charge-induced change in the electric field. The threshold current of such a semiconductor laser can be reduced to below 100 nA.