Browsing by Author "Kuo, Hao-Chun"

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Flexible random lasers with tunable lasing emissions
(2018-06-14)
Lee, Ya-Ju
;
Chou, Chun-Yang
;
Yang, Zu-Po
;
Thi Bich Hanh Nguyen
;
Yao, Yung-Chi
In this study, we experimentally demonstrated a flexible random laser fabricated on a polyethylene terephthalate (PET) substrate with a high degree of tunability in lasing emissions. Random lasing oscillation arises mainly from the resonance coupling between the emitted photons of gain medium (Rhodamine 6G, R6G) and the localized surface plasmon (LSP) of silver nanoprisms (Ag NPRs), which increases the effective cross-section for multiple light scattering, thus stimulating the lasing emissions. More importantly, it was found that the random lasing wavelength is blue-shifted monolithically with the increase in bending strains exerted on the PET substrate, and a maximum shift of similar to 15 nm was achieved in the lasing wavelength, when a 50% bending strain was exerted on the PET substrate. Such observation is highly repeatable and reversible, and this validates that we can control the lasing wavelength by simply bending the flexible substrate decorated with the Ag NPRs. The scattering spectrum of the Ag NPRs was obtained using a dark-field microscope to understand the mechanism for the dependence of the wavelength shift on the exerted bending strains. As a result, we believe that the experimental demonstration of tunable lasing emissions based on the revealed structure is expected to open up a new application field of random lasers.
Tunable random lasing emissions by manipulating plasmonic coupling strengths on flexible substrates
(2018-01-01)
Yeh, Ting-Wei
;
Chou, Chun-Yang
;
Yang, Zu-Po
;
Nguyen Thi Bich Hanh
;
Yao, Yung-Chi
A random laser is a unique system in which an assembly of disordered scatters is distributed all over the gain medium to sustain the required optical feedbacks by multiple scatterings for the stimulation of lasing action. Due to the absence of well-defined resonance cavity or rigid alignment of optical elements, it is hence difficult to control the random lasing emissions. In this study, we experimentally demonstrated a flexible random laser fabricated on the polyethylene terephthalate (PET) substrate with a high degree of tunability in lasing emissions. Random lasing wavelength is blue-shifted monolithically with the increasing of bending strains exerted on the PET substrate, and the maximum shift of lasing wavelength of similar to 15 nm was achieved as a 50% bending strain is exerted on the PET substrate. Such observation is highly repeatable and reversible, and it validates that we are able to control the lasing wavelengths by simply bending the flexible substrate. The result herein shows a great advance for the applications of flexible optoelectronic devices, including wearable devices, ultrathin display, and health sensors.