Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "An aspect of the present invention is a nanometer scale semiconductor laser source for on-chip integration. The laser can be very compact, with typical device dimensions of 50-200 nm.times.50-200 nm.times.2-20 .mu.m. The device is capable of efficient generation of sub-wavelength high intensity light and the potential for large modulation bandwidth >1 THz.
"The high efficiency and compact dimensions are achieved by the laser action of optical modes bound between the surface of a metal and a semiconductor structure. These optical modes have dimensions more than an order of magnitude smaller than the wavelength of the light, leading to intense optical fields on the nano-meter scale. The light source of the present invention may be employed to sense and detect ultra-small quantities of biomolecular species, and provide superior sensitivity and with lower power consumption. In addition, the device of the present invention is capable of fast laser modulation speed, and can be modulated up to at least 10 THz, providing unprecedented data bandwidth.
"Nanometer-scale plasmonic lasers are shown generating optical modes a hundred times smaller than the diffraction limit of light. In one embodiment, hybrid plasmonic waveguides comprise a high-gain cadmium sulphide semiconductor nanowire that is separated from a silver surface by a 5-nm thick insulating gap. Direct measurements of the emission lifetime reveal a broad-band enhancement of the nanowire's exciton spontaneous emission rate by up to six times, due to strong mode confinement and the signature of threshold-less lasing. Because plasmonic modes of the devices of the present invention have no cutoff, downscaling of the lateral dimensions of both the device and the optical mode have been shown. The plasmonic lasers of the present invention thus allow for study of extreme interactions between light and matter, with particular applicability in the fields of active photonic circuits, bio-sensing, and quantum information technology.
"The present invention uses surface plasmon polaritons to overcome the well established diffraction limit of conventional optics via the compact storage of optical energy in electron oscillations at the interfaces of metals and dielectrics. The subwavelength optical length scales allows for compact optical devices with new functionalities by enhancing inherently weak physical processes, such as fluorescence and Raman scattering of single molecules and nonlinear phenomena.
"The optical source of the present invention couples electronic transitions directly to strongly localized optical modes, and avoids the common limitations of delivering light from a macroscopic external source to the nanometer scale (e.g. low coupling efficiency and difficulties in accessing individual optical modes).
"Various applications of the system of the present invention, include, but are not limited to, (i) a sub-wavelength light source capable of focusing and sustaining input optical or electrical power to below the diffraction limit; (ii) integration with existing silicon photonic systems to provide new functionality including: nano-scale optical logic, enhanced non-linear effects for switching and optical processing; (iii) the basis for new ultra-sensitive detectors operating at the single molecule level, by utilizing enhanced light matter interactions within the confined environment.
"Furthermore, electrical pumping means may be used such that a small voltage (e.g.
"In one embodiment, an electrically driven plasmon nanowire laser is disclosed.
"In another embodiment, plasmon nanowire laser with a light emitting tunnel junction is disclosed.
"An aspect of the invention is a plasmon laser source, comprising a metal substrate, a semiconductor separated from a surface of the metal substrate by a low-refraction index gap, and an electron pumping means. The electron pumping means is configured to excite an electron carrier population to generate a plasmonic laser emission from the low-refraction index gap. The plasmonic laser emission is confined by a plasmonic mode having a mode size smaller than the diffraction limit of light in at least one dimension.
"Another aspect of the invention is method for generating a plasmonic emission having a mode size smaller than the diffraction limit of light, the method comprising the steps of: generating an electrical bias across a metal substrate and a semiconductor material separated from a surface of the metal substrate by a low-refraction index gap; and exciting an electron carrier population within the semiconductor material to generate the plasmonic emission from the low-refraction index gap.
"Further aspects of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the invention without placing limitations thereon."
For the URL and additional information on this patent, see: Zhang, Xiang; Sorger, Volker Jendrik; Oulton,
Keywords for this news article include: Electronics, Semiconductor, The Regents of the
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