Kevin Chih-Yao Huang

We report on violet-emitting III-nitride light-emitting diodes (LEDs) grown on bulk GaN substrates employing a flip-chip architecture. Device performance is optimized for operation at high current density and high temperature, by specific design consideration for the epitaxial layers, extraction efficiency, and electrical injection. The power conversion efficiency reaches a peak value of 84% at 85 􏰀 C and remains high at high current density, owing to low current-induced droop and low se- ries… Show more

We report on violet-emitting III-nitride light-emitting diodes (LEDs) grown on bulk GaN substrates employing a flip-chip architecture. Device performance is optimized for operation at high current density and high temperature, by specific design consideration for the epitaxial layers, extraction efficiency, and electrical injection. The power conversion efficiency reaches a peak value of 84% at 85 􏰀 C and remains high at high current density, owing to low current-induced droop and low se- ries resistance. Show less

Metal-dielectric-metal (MDM) waveguides for surface-plasmon-polaritons (SPPs) exhibit single-mode operation without cutoff, strong spatial confinement and field enhancements for optical light while accommodating simultaneous electrical functions. These desirable properties allow optical energy confined within the slot to interact strongly with the sandwiched semiconductor materials for enhanced absorption and tailored emission into desired modes or directions. Here, we demonstrate for the first… Show more

Metal-dielectric-metal (MDM) waveguides for surface-plasmon-polaritons (SPPs) exhibit single-mode operation without cutoff, strong spatial confinement and field enhancements for optical light while accommodating simultaneous electrical functions. These desirable properties allow optical energy confined within the slot to interact strongly with the sandwiched semiconductor materials for enhanced absorption and tailored emission into desired modes or directions. Here, we demonstrate for the first time, electrical generation of three-dimensionally (3D) confined slot MDM SPPs with a cross-sectional mode area of 0.016 λ2 and propagation length of ~ 8 μm. We fabricated metal-clad cavity nano-light-emitting diode (n-LED) based on InGaAs/ GaAs quantum well which is directly coupled to a suspended symmetric Au MDM slot waveguide. Our plasmon-emitting diodes (PED) can achieve high coupling efficiency and packing density. The platform support two-dimensional (2D) routing, splitting and directional coupling of SPPs which will enable optical nano-circuits for interconnects and high throughput sensing in nanometric volumes. Show less

Optical antennas can control the radiation from optically excited quantum emitters by modifying the local density of optical states via the Purcell effect. A variety of nanometallic antennas have been implemented to enhance and control key photoluminescence properties, such as the decay rate, directionality, and polarization. However, their implementation in active devices has been hampered by the need to precisely place emitters near an antenna and to efficiently excite them electrically. We… Show more

Optical antennas can control the radiation from optically excited quantum emitters by modifying the local density of optical states via the Purcell effect. A variety of nanometallic antennas have been implemented to enhance and control key photoluminescence properties, such as the decay rate, directionality, and polarization. However, their implementation in active devices has been hampered by the need to precisely place emitters near an antenna and to efficiently excite them electrically. We realize antenna-electrodes which for the first time facilitate simultaneous operation as electrodes for current injection into nanoscale light-emitting diodes and as antennas capable of optically manipulating the electroluminescence. We illustrate design methodology for antenna-electrodes capable of effectively couple the emission from excitons to antenna modes by confining their electrical excitation to the antenna's vicinity. This work spurs the development of densely-integrated, electrically-driven light sources with unconventional emission properties. Show less

Current methods to calculate the emission enhancement of a quantum emitter coupled to an optical antenna of arbitrary geometry rely on analyzing the total Poynting vector power flow out of the emitter or the dyadic Green functions from full-field numerical simulations. Unfortunately, these methods do not provide information regarding the nature of the dominant energy decay pathways. We present a new approach that allows for a rigorous separation, quantification, and visualization of the emitter… Show more

Current methods to calculate the emission enhancement of a quantum emitter coupled to an optical antenna of arbitrary geometry rely on analyzing the total Poynting vector power flow out of the emitter or the dyadic Green functions from full-field numerical simulations. Unfortunately, these methods do not provide information regarding the nature of the dominant energy decay pathways. We present a new approach that allows for a rigorous separation, quantification, and visualization of the emitter output power flow captured by an antenna and the subsequent reradiation power flow to the far field. Such analysis reveals unprecedented details of the emitter/antenna coupling mechanisms and thus opens up new design strategies for strongly interacting emitter/antenna systems used in sensing, active plasmonics and metamaterials, and quantum optics. Show less