Purcell-enhanced electroluminescence of a unipolar light-emitting quantum device at λ = 10 µ m

Efficient generation of radiation in the mid- and far-infrared relies primarily on lasers and coherent nonlinear optical phenomena driven by lasers. This wavelength range lacks practical and efficient luminescent devices, particularly, because the spontaneous emission rate becomes much longer than the nonradiative energy relaxation processes and therefore emitters have to count on stimulated emission produced by linear or nonlinear optical gain. However, spontaneous emission is not a fundamental property of the emitter. By engineering metamaterials composed of arrays of nanoemitters into microcavities coupled to patch antennas, we have demonstrated midinfrared electroluminescent devices emitting a collimated beam with excellent spatial properties and a factor of 100 increase in the collected power, compared to standard devices. Our results illustrate that by reshaping the photonic environment around emitting dipoles, as in the Purcell effect, it is possible to enhance the spontaneous emission and conceive efficient optoelectronic light-emitting devices that operate close to the thermodynamical equilibrium as light-emitting diodes in the visible range.