Total-reflection active-mirror amplifier for high pulse energy and high average power by using a composite ceramic

A total-reflection active-mirror (TRAM) amplifier is functionally designed by using a composite ceramic for high pulse energy and high average power. A chirped-pulse regenerative amplifier with a cryogenic TRAM has been successfully demonstrated as a feasibility study. A 3.5 mJ pulse energy is obtained at a repetition rate of 100 Hz. The corresponding energy fluence on the TRAM is as high as 1.5 J/cm² for 0.46 ns short pulses. The M²-factor is below 1.1 and no significant beam distortion is observed.     

Coupled nanowire-based hybrid plasmonic nanocavities on thin substrates

We theoretically analyze nanowire-based hybrid plasmonic nanocavities on thin substrates at visible wavelengths. In the presence of thin suspended substrates, the hybrid plasmonic modes, formed by the coupling between a metal nanowire and a dielectric nanowire with optical gain, exhibit negligible substrate-mediated characteristics and overlap better with the gain region. Consequently, the confinement factor of the guided hybrid modes is enhanced by more than 42%. However, the presence of significant mirror loss remains the main challenge to lasing. By adding silver coatings with a sufficient thickness range on the two end facets, we show that the reflectivity is substantially enhanced to above 50%. For a coating thickness of 50 nm and cavity length of about 4 μm, the quality factor is above 100.     

Tuning color-correlated temperature and color rendering index of phosphorescent white polymer light-emitting diodes: Towards healthy solid-state lighting

We report on efficient solution-processed phosphorescent white polymer light-emitting diodes (WPLEDs) with tunable color-correlated temperature (CCT) and color rendering index (CRI), through rationally controlling the composition of the emission layer (EML) based on a near-infrared (NIR)-emitting dinuclear cyclometalated platinum (II) complex bridged with NˆS anionic ligand, named (niq)₂Pt₂(μ-C₈PhOXT)₂ (Pt-1, in which PhOXT is 5-(phenyl-1,3,4-oxadiazole)-2-thiol, niq is 1-naphthylisoquinolinato), a sky-blue emitter iridium (III) bis[(4,6-di-fluorophenyl)-pyridinato-N,C2] (picolinate) (FIrpic), and a yellow emitter bis[2-(thieno[3,2-c]pyridin-4-yl)phenyl]iridium(III)(acetylacetonato) (PO-01). One of the best three-color WPLEDs shows a CCT of 3246 K as well as an excellent high CRI of 87, which are greatly beneficial in reducing deep-blue light damage and simultaneously meet the requirement for good color reproduction. Meanwhile, the relevant WPLED also achieves a maximum current efficiency of 12.1 cd/A, corresponding to an external quantum efficiency of 10.6%. This work presents an effective approach through rational combination of sky-blue, yellow, and NIR emitters towards high-performance solution-processable WPLEDs with a physiologically-friendly CCT and a high CRI.     

A new compact circuit-level model of semiconductor lasers: investigation of relative intensity noise and frequency noise spectra

We introduce a new compact noise equivalent circuit model of semiconductor lasers (SLs) from the rate equation including Langevin noise sources. The noise sources are described in terms of the spectral properties of the relative intensity noise (RIN) and frequency/phase noise (FN). Unlike the previous noise equivalent circuit models, which are based on two different DC and small-signal circuit models, using only a single circuit model, the static and dynamic responses and also the noise characteristics of SLs, can be investigated. We examine the validity of the presented noise circuit model by comparing the simulated results with the analytical and numerical results available in the literatures.     

Processing and characterization of an Li7La3Zr0.5Nb0.5Ta0.5Hf0.5O12 high-entropy Li–garnet electrolyte

In this paper, we demonstrated the processing of Li₇La₃Zr_0.5Nb_0.5Ta_0.5Hf_0.5O₁₂ (LLZNTH) high-entropy Li–garnet with promising properties for lithium batteries. We first synthesized the LLZNTH Li–garnet powders which have a single cubic garnet phase (space group: $\text{◂⋅▸}Ia\overline{3}d$; No. 230) without any secondary phases as well as uniform elements distributions. The prepared powders were further densified to a relative density of ∼94% with well-crystallized grains and good contact with the neighboring grains. Minimal grain growth can be observed in the sintering time range from 8 to 20 h, which is likely due to the sluggish effects of high-entropy compounds. The sample also maintains the cubic garnet phase along with uniform elements distribution after sintering. Electrochemical characterizations indicate that the densified sample has an adequate ionic conductivity of 4.67 × 10⁻⁴ S cm⁻¹ at room temperature, a low activation energy of 0.25 eV, and a low electronic conductivity in the order of 10⁻⁸ S cm⁻¹. The significance of designing high-entropy electrolyte is further discussed.     

Energy issues in microwave food processing: A review of developments and the enabling potentials of solid-state power delivery

The enormous magnitude and variety of microwave applications in household, commercial and industrial food processing creates a strong motivation for improving the energy efficiency and hence, sustainability of the process. This review critically assesses key energy issues associated with microwave food processing, focusing on previous energy performance studies, energy performance metrics, standards and regulations. Factors affecting energy-efficiency are categorised into source, load and source-load matching factors. This highlights the need for highly-flexible and controllable power sources capable of receiving real-time feedback on load properties, and effecting rapid control actions to minimise reflections, heating non-uniformities and other imperfections that lead to energy losses. A case is made for the use of solid-state amplifiers as alternatives to conventional power sources, magnetrons. By a full-scale techno-economic analysis, including energy aspects, it is shown that the use of solid-state amplifiers as replacements to magnetrons is promising, not only from an energy and overall technical perspective, but also in terms of economics.     

Study on thermolysis process of a new hydrated and protonated perovskite-like oxides H2K0.5Bi2.5Ti4O13·yH2O

A protonated form of the n?=?4 layered bismuth containing perovskite-like titanate K_2.5Bi_2.5Ti₄O₁₃ belonging to Ruddlesden-Popper phases was prepared via ion exchange reaction of interlayer K⁺ with protons. Its composition was investigated by TG ICP and EDX analysis was found to be H₂K_0.5Bi_2.5Ti₄O₁₃·H₂O. The thermal behavior of the obtained phase was investigated by STA coupled with mass-spectrometry, the structural changes, happening with the sample during heating, were examined by XRD. It was shown that the as-prepared hydrated phase undergoes two-stage dehydration at low temperatures (up to 160?°C). The further heating leads to the gradual decomposition and crystallization of new phases, notably Bi₂Ti₂O₇, Bi₄Ti₃O₁₂ and Bi₂Ti₄O₁₁. The morphology of the as-prepared sample and samples after heat treatment was examined using SEM.