Nanolasers employing epitaxial plasmonic layers

Miniaturization of semiconductor lasers holds the key to the development of compact, low-threshold, and fast coherent on-chip light sources/amplifiers, which are critically important for emerging applications in nanophotonics, integrated optics, and information technology (1-3). However, on-chip integration of nanoscale electronic components with conventional semiconductor lasers utilizing dielectric optical cavities is impeded by the diffraction limit-i.e., ∼(λ/2n)³ for three-dimensional (3D) cavities, where λ is the free-space wavelength and n is the refractive index of the dielectric (4-7). The recent advent of nanoplasmonics based on metallodielectric structures has led to the design of optical components and optoelectronic devices in the deep subwavelength regime (8-13). In particular, a new class of lasers based on surface plasmon amplification by stimulated emission of radiation (SPASER) has recently been proposed (14, 15) and experimentally demonstrated (16-19). In the SPASER operation, surface plasmons excited in noble-metal structures adjacent to gain media dramatically increase the optical mode density, shrink the optical mode volume, and provide the necessary feedback mechanism.