Browsing by Author "Her, Tsing-Hua"

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Femtosecond-laser ablation of monolayer molybdenum disulfide (MoS2) on sapphire
(2019-01-01)
Solomon, Joel M.
;
Yao, Hsin-Yu
;
Lu, Li-Syuan
;
Chang, Wen-Hao
;
Her, Tsing-Hua
Single-shot femtosecond laser ablation of monolayer molybdenum disulfide is demonstrated. An ablation threshold was found 0.9 nJ/mu m(2), which is too low for two-photon photoionization alone. We show that surface defects and avalanche ionization are important. (C) 2019 The Author(s)
Femtosecond-Laser Ablation of Monolayer Tungsten Diselenide (WSe2) on Sapphire
(2018-01-01)
Chen, Yu-Ling
;
Tseng, Ya-Hsin
;
Chen, Yen-Chun
;
Chang, Wen-Hao
;
Her, Tsing-Hua
Near-IR femtosecond laser ablation of monolayer tungsten diselenide WSe2 on sapphire is demonstrated. The ablation threshold is found low (below 10 mJ/cm(2)), due to its low dimensionality and weak coupling to substrates. Substrate-dependent ablation threshold is predicted and will be discussed.
Low-Threshold Plasmonic Lasers on a Single-Crystalline Epitaxial Silver Platform at Telecom Wavelength
(2017-06-01)
Lee, Chien-Ju
;
Yeh, Han
;
Cheng, Fei
;
Su, Ping-Hsiang
;
Her, Tsing-Hua
We report on the first demonstration of metal insulator semiconductor-type plasmonic lasers at the telecom wavelength (similar to 1.3 mu m) using top-down fabricated semiconductor waveguides on single-crystalline metallic platforms formed using epitaxially grown Ag films. The critical role of the Ag film thickness in sustaining. plasmonic lasing at the telecom wavelength is investigated systematically. Low-threshold (0.2 MW/cm(2)) and continuous-wave operation of plasmonic lasing at cryogenic temperatures can be achieved on a 150 nm Ag platform with minimum radiation leakage into the substrate. Plasmonic lasing occurs preferentially through higher-order surface-plasmon-polariton modes, which exhibit a higher mode confinement factor, lower propagation loss, and better field gain coupling. We observed plasmonic lasing up to 200 K under pulsed excitations. The plasmonic lasers on large-area epitaxial Ag films open up a scalable platform for on-chip integrations of plasmonics and optoelectronics at the telecom wavelength.