IBM Corp.'s Thomas J. Watson Research Center is bringing silicon photonics one step closer to reality by putting a light-emitting nanotube (LEN) inside an optical waveguide to achieve directional surface emission, wavelength selectivity and the potential for ultrahigh efficiency. By fabricating an optical cavity around a light-emitting nanotube (see figure) mirrors at the bottom and top confine wavelengths to the desired 1.55 micron communications frequency. The bottom mirror was made from silver, with a top half-mirror made from gold. Light was emitted from the nanotube in the cavity, which was filled with transparent dielectric.

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