Yaoguang Ma

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We report direct coupling of plasmonic and photonic nanowires using ultracompact near-field interaction. Photon-plasmon coupling efficiency up to 80% with coupling length down to the 200 nm level is achieved between individual Ag and ZnO nanowires. Hybrid nanophotonic components, including polarization splitters, Mach-Zehnder interferometers, and microring(More)
Single-mode plasmonic waveguiding properties of metal nanowires with dielectric substrates are investigated using a finite-element method. Au and Ag are selected as plasmonic materials for nanowire waveguides with diameters down to 5-nm-level. Typical dielectric materials with relatively low to high refractive indices, including magnesium fluoride (MgF2),(More)
Monolayer molybdenum disulphide (MoS2) has attracted much attention, due to its attractive properties, such as two-dimensional properties, direct bandgap, valley-selective circular dichroism, and valley Hall effect. However, some of its fundamental physical parameters, e.g. refractive index, have not been studied in detail because of measurement(More)
We report on the fabrication of three-dimensional (3D) high-Q whispering gallery microcavities on a fused silica chip by femtosecond laser microfabriction, enabled by the 3D nature of femtosecond laser direct writing. The processing mainly consists of formation of freestanding microdisks by femtosecond laser direct writing and subsequent wet chemical(More)
We demonstrate a simple, direct measurement of propagation losses in single silver nanowires. Using a waveguiding nanoscale fiber taper for highly efficient launching, propagation surface plasmon polaritons are excited in the silver nanowire with high efficiency. The output intensity as light radiation at the end of the nanowire is quantified with high(More)
Passive radiative cooling draws heat from surfaces and radiates it into space as infrared radiation to which the atmosphere is transparent. However, the energy density mismatch between solar irradiance and the low infrared radiation flux from a near-ambient-temperature surface requires materials that strongly emit thermal energy and barely absorb sunlight.(More)
We demonstrate a dynamic surface plasmonic modulation based on graphene-nanowire (grapheme-NW) hybrid structures in the visible light range. A static modulation depth of as high as 0.07 dB/μm has been achieved experimentally. Through careful simulation and systematical experimental investigation, we found that the dual-confinement effect of charge density(More)
Designing lasing wavelengths and modes is essential to the practical applications of nanowire (NW) lasers. Here, according to the localized photoluminescence spectra, we first demonstrate the ability to define lasing wavelengths over a wide range (up to 119 nm) based on an individual bandgap-graded CdSSe NW by forward cutting the NW from CdSe to CdS end.(More)
Multicolour lasing with wavelength varying from 578 nm to 640 nm is realized from a single bandgap-graded CdSSe alloy nanoribbon, by selecting the excited spot at room temperature. Though reabsorption is a serious problem to achieve lasing at short wavelength, multiple scatters on the nanoribbon form localized cavities, and thus lasing at different(More)
Graphene is a favorable candidate for electrodes of organic light emitting diodes (OLEDs). Graphene has quite a high work function of ∼4.5 eV, and has been extensively studied when used as anodes of OLEDs. In order to use graphene as a cathode, the electron injection barrier between the graphene cathode and the electron transport layer has to be low enough.(More)