Cavities of crystal light [photonic crystal microcavities]

This paper presents the characteristics of photonic crystal microcavity light sources. Microcavities with dimensions on the scale of the wavelength of light are being extensively investigated due to their ability to exhibit enhanced spontaneous emission, directional output, and single-mode operation. Photonic crystals, which are the optical analog of semiconductors in electronic devices, are capable of controlling the properties of light by confining photons in one, two, or three dimensions. The technology to fabricate photonic crystals at the optical-wavelength scale (i.e., feature sizes at the submicron scale) has only very recently been achieved. Single or multiple defects in the photonic crystals act as microcavities with dimensions on the order of the wavelength of light and have emerged as the preferred way to obtain defect-free optical microcavities. The authors have been investigating electrically injected photonic crystal microcavities, and these devices are described in this paper. Electrically injected microcavities offer the advantage of possible integration with current optoelectronic circuits and devices. Also, arrays of such devices can be fabricated when electrically controlled. Electrically injected photonic crystal microcavity light sources may also realize high-efficiency single-mode LEDs.