Abel Carney (selectslime62)

We have performed cavity dumping of a diode-pumped alkali laser (DPAL) and have observed a saw-like structure in the pulse waveform that appears to be caused by interference between two or more longitudinal modes. We have confirmed that multimode oscillations are caused by spatial hole burning, and the largest peak was seen when only two oscillation modes were present. This phenomenon may be useful for enhancing the cavity dumping of the DPAL, but it was not always observed. Therefore, we developed a numerical simulation to predict the number of longitudinal modes excited under a given set of conditions and provides guidelines to facilitate dual-mode oscillation. Using these guidelines, we have obtained a pulse with a peak power of 250 W, which is higher than the average power circulating in the cavity and is a 38-fold enhancement of the continuous-wave (CW) output.Presbyopia is the failure of the eye lens to accommodate. The widely used presbyopia correction method involves wearing bi/trifocal or progressive glasses, which limits the field of view due to division of lens area into sections of different optical power. A large aperture focus tunable liquid crystal lens has the potential to correct human eye accommodation failure and provide a wide field of view. learn more In this paper, we present characterization and demonstration of a segmented phase profile liquid crystal lens, which has the characteristics of a large area (diameter 20 mm), being flat and thin ( less then 2 mm), and having continuous focus tunability (1.5 D to 0 D), fast response time ( less then 500 ms), low operating voltage ( less then 5 V), and on-axis diffraction-limited performance (for a 5mm aperture). Considering all these properties, our lens provides performance details of an approach for presbyopia correction. We have tested the minimum resolution and visual acuity of 20 subjects using the designed lens and compared the results with a reference glass lens of the same optical power.Inverted quantum dot light-emitting diodes (QLEDs) were fabricated through all-solution processing by sandwiching quantum dot (QD) emitting layers (EMLs) between dual polyethylenimine-ethoxylated (PEIE) layers. First, a PEIE layer as EML protecting layer (EPL) was formed on a QD EML to protect the EML from the hole transport layer (HTL) solvents and to facilitate the formation of a well-organized structure in the all-solution-processed inverted QLEDs. Second, another PEIE layer was introduced as an electron-blocking layer (EBL) on the zinc oxide (ZnO) electron transport layer (ETL) and effectively suppressed the excessive electron injection to the QD EML, thereby enhancing device efficiency.Engineered spherical micro-lens can manipulate light at sub-wavelength scale and emerges as a promising candidate to extend the focal length and narrow the focal spot size. Here, we report the generation of photonic nanojets (PNJs) with an ultralong working distance and narrowed beam waist by an immersed engineered hemisphere. Simulations show that a two-layer hemisphere of 4.5 µm radius exhibits a PNJ with the working distance of 9.6 µm, full width at half maximum of 287 nm, and length of 23.37 λ, under illumination of a plane wave with a 365 nm wavelength. A geometrical optics analysis indicated that the formed PNJ behind the immersed two-layer hemisphere results from the convergence of light of the outer-hemisphere fringe area, which refracts into and passes through the outer hemisphere and then directly leaves the outer-hemisphere flat surface. Thus the embedded hemisphere is comparable to an immersed focusing lens with high numerical aperture, which can promise both long working distance and narrowed beam waist. This is further demonstrated with the corresponding embedded-engineered single-layer hemisphere, whose spherical face is partly cut parallel to the hemispherical flat surface. In addition, the hemisphere is compatible with adjacent laser wavelengths. Finally, a spot