Phys. Rev. Lett. 107, 193903 (2011)

Credit: © 2011 APS

One of the defining features of photonic crystals is that they block the propagation of light of certain wavelengths. Within these forbidden gaps, even light emission is suppressed. This effect has now been demonstrated by Willem Vos and colleagues in a silicon photonic crystal with a full three-dimensional photonic bandgap. Etched out of silicon with nanometre precision utilizing a fully CMOS-compatible process — in itself a remarkable, pioneering achievement — the photonic crystals have their bandgap at near-infrared telecommunications wavelengths. The photonic crystals were placed in a solution containing PbS quantum dots, whose emission wavelength is matched to the photonic crystals band gap. Compared with the quantum dots outside, light emission from the quantum dots within the photonic crystal is considerably suppressed, by up to a factor of ten for wavelengths within the photonic bandgap. This light-suppression effect could be useful for situations where spontaneous light emission such as that from the quantum dots represents an undesirable noise, for example in lasers or in optical quantum computers.