RESUMO
Augmenting fluorescence intensity is of vital importance to the development of chemical and biochemical sensing, imaging and miniature light sources. Here we report an unprecedented fluorescence enhancement with a novel architecture of multilayer three-dimensional colloidal photonic crystals self-assembled from polystyrene spheres. The new technique uses a double heterostructure, which comprises a top and a bottom layer with a periodicity overlapping the excitation wavelength (E) of the emitters, and a middle layer with a periodicity matching the fluorescence wavelength (F) and a thickness that supports constructive interference for the excitation wavelength. This E-F-E double heterostructure displays direction-dependent light trapping for both excitation and fluorescence, coupling the modes of photonic crystal with multiple-beam interference. The E-F-E double heterostructure renders an additional 5-fold enhancement to the extraordinary FL amplification of Rhodamine B in monolithic E CPhCs, and 4.3-fold acceleration of emission dynamics. Such a self-assembled double heterostructure CPhCs may find significant applications in illumination, laser, chemical/biochemical sensing, and solar energy harvesting. We further demonstrate the multi-functionality of the E-F-E double heterostructure CPhCs in Hg (II) sensing.
RESUMO
We report 32% efficient frequency doubling of single-frequency 1029 nm light to green light at 514.5 nm using a single-pass configuration. A congruent composition, periodically poled magnesium-doped lithium niobate (PPMgLN) crystal of 50 mm length was used to generate a second-harmonic power of 2.3 W. To our knowledge, this is the highest reported power and efficiency achieved in the second-harmonic generation of single-frequency green light in a single-pass configuration.
