Browsing by Author "Conti, Claudio"

Now showing 1 - 3 of 3

Curvature-assisted wave localization in Vertical Cavity Surface Emitting Lasers
(2017-01-01)
Hong, Kou-Bin
;
Lin, Chun-Yan
;
Chang, Tsu-Chi
;
Liang, Wei-Hsuan
;
Lai, Ying-Yu
By implementing surface structures in vertical cavity surface emitting lasers as manifolds for curved space, we experimentally study the impacts of geometrical constraints on wave localization. We observe localized waves pinned to the maximal curvature in an ellipticalring, and confirm the reduction in the localization length of waves by measuring near and far field patterns, as well as the corresponding dispersion relation. Theoretically, analyses based on a dissipative model with a parabola curve give good agreement remarkably to experimental measurement on the transition from delocalized to localized waves. The introduction of curved topology allows to control and design lasing modes in the nonlinear regime.
Flexible Organometal-Halide Perovskite Lasers for Speckle Reduction in Imaging Projection
(2019-05-01)
Wang, Yu-Chi
;
Li, Heng
;
Hong, Yu-Heng
;
Hong, Kuo-Bin
;
Chen, Fang-Chung
Disorder is emerging as a strategy for fabricating random laser sources with very promising materials, such as perovskites, for which standard laser cavities are not effective or too expensive. We need, however, different fabrication protocols and technologies for reducing the laser threshold and controlling its emission. Here, we demonstrate an effectively solvent-engineered method for high-quality perovskite thin films on a flexible polyimide substrate. The fractal perovskite thin films exhibit excellent optical properties at room temperature and easily achieve lasing action without any laser cavity above room temperature with a low pumping threshold. The lasing action is also observed in curved perovskite thin films on flexible substrates. The lasing threshold can be further reduced by increasing the local curvature, which modifies the scattering strengths of the bent thin film. We also show that the curved perovskite lasers are extremely robust with respect to repeated deformations. Because of the low spatial coherence, these curved random laser devices are efficient and durable speckle-free light sources for applications in spectroscopy, bioimaging, and illumination.
Lasing on nonlinear localized waves in curved geometry
(2017-11-13)
Hong, Kou-Bin
;
Lin, Chun-Yan
;
Chang, Tsu-Chi
;
Liang, Wei-Hsuan
;
Lai, Ying-Yu
The use of geometrical constraints exposes many new perspectives in photonics and in the fundamental studies of nonlinear waves. By implementing surface structures in vertical cavity surface emitting lasers as manifolds for curved space, we experimentally study the impacts of geometrical constraints on nonlinear wave localization. We observe localized waves pinned to the maximal curvature in an elliptical-ring, and confirm the reduction in the localization length of waves by measuring near and far field patterns, as well as the corresponding energy-angle dispersion relation. Theoretically, analyses based on a dissipative model with a parabola curve give good agreement remarkably to experimental measurement on the reduction in the localization length. The introduction of curved geometry allows to control and design lasing modes in the nonlinear regime. (C) 2017 Optical Society of America