RESUMO
We report single-mode and multimode lasing from isolated spherical liquid microcavities containing CdSe/ZnS nanocrystal quantum dots. Lasing is observed at densities more than 2 orders of magnitude lower than previously demonstrated or theoretically predicted, assuming a uniform nanocrystal quantum dot distribution. Charged droplets, between 10 and 40 microm in size, are electrodynamically levitated and optically pumped. Substantial laser signals at low thresholds are measured from the directional emission normal to the pump beam, owing to the high Q cavity modes.
Assuntos
Lasers , Pontos Quânticos , Desenho de Equipamento , Análise de Falha de EquipamentoRESUMO
We present the design of a simple, modular, and inexpensive generator for droplets with diameters of 20-150 microm. The instrument is based on piezoelectric pressure injection. Its main components, their functionality, and instructions for reliable operation are described in detail. The option of charging microdrops is also discussed.
Assuntos
Injeções/instrumentação , Microfluídica/instrumentação , Soluções/química , Desenho de Equipamento , Análise de Falha de Equipamento , Injeções/métodos , Microfluídica/métodos , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
Strongly enhanced second-harmonic generation is observed from a two-dimensional square lattice GaAs/AlGaAs photonic crystal waveguide when the fundamental beam, the second-harmonic beam, or both beams resonantly couple to a leaky eigenmode. P-polarized second-harmonic spectra are obtained for s-polarized, 150-fs pump pulses that are tuned from 5000 to 5600 cm(-1) and directed along the gamma-chi direction of the crystal for various angles of incidence. Compared with off-resonant conditions, enhancements of >1200x in the second-harmonic conversion are observed for resonant coupling of both the fundamental and the second-harmonic fields to leaky eigenmnodes. The angular and spectral positions of the peaks are in good agreement with simulations.
