Browsing by Author "Lu, Yu-Jung"

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All-Color Plasmonic Nanolasers with Ultralow Thresholds
(2013)
Lu, Yu-Jung
;
Kim, Jisun
;
Chen, Hung-Ying
;
Chang, Wen-Hao
;
Shih, Chih-Kang
Diffraction-unlimited semiconductor nanolasers are demonstrated by using single shape-controlled InGaN/GaN core-shell nanorods as laser gain media on Ag films epitaxially grown on Si substrates. The use of atomically smooth Ag films allows us to fabricate low-loss plasmonic cavities for ultralow-threshold, continuous-wave (CW) nanolaser operation above liquid nitrogen temperature. Furthermore, the tunable band-gap energy of the InxGa1-xN alloy makes it possible to realize laser emission in the full visible spectrum.
All-Color Plasmonic Nanolasers with Ultralow Thresholds: Autotuning Mechanism for Single-Mode Lasing
(2014-08-01)
Lu, Yu-Jung
;
Wang, Chun-Yuan
;
Kim, Jisun
;
Chen, Hung-Ying
;
Lu, Ming-Yen
We report on the first demonstration of broadband tunable, single-mode plasmonic nanolasers (spasers) emitting in the full visible spectrum. These nanolasers are based on a single metal oxide semiconductor nanostructure platform comprising of InGaN/GaN semiconductor nanorods supported on an Al2O3-capped epitaxial Ag film. In particular, all-color lasing in subdiffraction plasmonic resonators is achieved via a novel mechanism based on a property of weak size dependence inherent in spasers. Moreover, we have successfully reduced the continuous-wave (CW) lasing thresholds to ultrasmall values for all three primary colors and have clearly demonstrated the possibility of "thresholdless" lasing for the blue plasmonic nanolaser.
All-Color Plasmonic Nanolasers with Ultralow Thresholds: Autotuning Mechanism for Single-Mode Lasing
(2014-08-01)
Lu, Yu-Jung
;
Wang, Chun-Yuan
;
Kim, Jisun
;
Chen, Hung-Ying
;
Lu, Ming-Yen
We report on the first demonstration of broadband tunable, single-mode plasmonic nanolasers (spasers) emitting in the full visible spectrum. These nanolasers are based on a single metal oxide semiconductor nanostructure platform comprising of InGaN/GaN semiconductor nanorods supported on an Al2O3-capped epitaxial Ag film. In particular, all-color lasing in subdiffraction plasmonic resonators is achieved via a novel mechanism based on a property of weak size dependence inherent in spasers. Moreover, we have successfully reduced the continuous-wave (CW) lasing thresholds to ultrasmall values for all three primary colors and have clearly demonstrated the possibility of "thresholdless" lasing for the blue plasmonic nanolaser.
Diffraction-Unlimited Plasmonic Nanolaser
(2015-01-01)
Lu, Yu-Jung
;
Kim, Jisun
;
Chen, Hung-Ying
;
Wu, Chihhui
;
Dabidian, Nima
High optical nonlinearity in low-dimensional halide perovskite polycrystalline films
(2020-08-17)
Liang, Wei-Yun
;
Liu, Fangzhou
;
Lu, Yu-Jung
;
Popovic, Jasminka
;
Djurisic, Aleksandra
The nonlinear optical properties of low-dimensional polycrystalline halide perovskite films consisting of ethylammonium (EA) and butylammonium (BA) cations are investigated using Z-scan technique. Across the band-edge, two-dimensional (BA)(2)PbI4 exhibits a transition from saturable absorption (SA) to reverse-SA and its nonlinear absorption and nonlinear refractive index are much smaller than those of bulk counterparts. Meanwhile, EAPbI(3) with one-dimensionality of the inorganic structure shows the SA behavior both above and below band-edge and the estimated nonlinear optical parameters of polycrystalline EAPbI(3) are comparable to those of single-crystalline ones, attributed to high dielectric contrast between the inorganic and organic elements in one-dimensional structures. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Nanolasers Employing Epitaxial Plasmonic Layers
(2013-01-01)
Lu, Yu-Jung
;
Kim, Jisun
;
Chen, Hung-Ying
;
Wu, Chihhui
;
Sanders, Charlotte E.
Plasmonic Nanolaser Using Epitaxially Grown Silver Film
(1970-01-01)
Lu, Yu-Jung
;
Kim, Jisun
;
Chen, Hung-Ying
;
Wu, Chihhui
;
Dabidian, Nima
"A nanolaser is a key component for on-chip optical communications and computing systems. Here, we report on the low-threshold, continuous-wave operation of a subdiffraction nanolaser based on surface plasmon amplification by stimulated emission of radiation. The plasmonic nanocavity is formed between an atomically smooth epitaxial silver film and a single optically pumped nanorod consisting of an epitaxial gallium nitride shell and an indium gallium nitride core acting as gain medium. The atomic smoothness of the metallic film is crucial for reducing the modal volume and plasmonic losses. Bimodal lasing with similar pumping thresholds was experimentally observed, and polarization properties of the two modes were used to unambiguously identify them with theoretically predicted modes. The all-epitaxial approach opens a scalable platform for low-loss, active nanoplasmonics."
Plasmonic Nanolaser Using Epitaxially Grown Silver Film
(2012-01-01)
Lu, Yu-Jung
;
Kim, Jisun
;
Chen, Hung-Ying
;
Wu, Chihhui
;
Dabidian, Nima
Successful development of epitaxial Ag as a new plasmonic platform has enabled low-threshold, continuous-wave (CW) operation of a SPASER-enabled nanolaser comprised of a subdiffraction plasmonic cavity and a single InGaN@GaN core-shell nanorod gain medium.
( )Ultrafast Exciton Dynamics in Scalable Monolayer MoS2 Synthesized by Metal Sulfurization
(2020-05-19)
Tsai, Hsu-Sheng
;
Huang, Yung-Hung
;
Tsai, Po Cheng
;
Chen, Yi-Jia
;
Ahn, Hyeyoung
Excitons in monolayer transition metal dichalcogenides (TMDs) have exceptionally large binding energies and dominate the optical properties of materials. Exploring the relaxation behavior of excitons is crucial for understanding the fundamental physics as well as the performance of TMD-based optoelectronic devices. However, ultrafast carrier dynamics is sensitive to the structural defects and surface conditions of TMDs, depending on the growth or transfer process. Here, we utilized pump-probe transient absorption (TA) spectroscopy with a white-light probe to investigate the dynamics of excitons in monolayer MoS2 synthesized by the metal sulfurization method. The sulfurization method was used for the fabrication of large-scale, continuous, and uniform thin films with a controllable number of layers. The excitation dynamics of the wafer-size monolayer MoS2 is found to be comparable to that of monolayer MoS2 flakes grown by chemical vapor deposition (CVD). The dominant processes of carrier relaxation in the monolayer MoS2 are exciton-exciton annihilation (hundreds of femtoseconds), the trapping of the excitons by surface states (a few picoseconds), and interband carrierphonon scattering (tens of picoseconds). Moreover, the induced absorption due to mid-gap defects, which is often observed for samples fabricated by growth methods, such as CVD, is not observed for our continuous and uniform monolayer films. Understanding the charge carrier dynamics of the exciton in the scalable and uniform monolayer MoS2 can provide physical insights that are valuable in the design and development of complex 2D devices.