Lead-halide perovskites have attracted tremendous attention, initially for their performance in thin film photovoltaics, and more recently a variety of remarkable optical properties. Defect tolerance through polaron formation within the ionic lattice is key aspect these materials. Polaron arises from dynamical coupling atomic fluctuations to electronic states. Measuring properties therefore essential light potential optoelectronic applications. Here we apply two-dimensional spectroscopy...

We report experimental results on gain medium area scaling of laser output power for large-area, transverse rf discharge excited carbon dioxide lasers. Power extraction to 20 kW/m2 has been achieved, indicating the significant potential this technique.

A technique has been developed for the localized treatment of laser damage sites in fused silica optics by CO2 melt-flow smoothing, using a 50 to 125 microm diameter beam regime that avoids mass removal ablation. detailed calibration irradiance threshold ablation craters was carried out range diameters and pulses 20 micros 200 ms range. The results agree with thermal model also provides estimates melt depth different irradiation conditions. Smoothing trials glass melting at values just below...

A one-dimensional unstable resonator combining free-space and waveguide propagation is used to efficiently extract power from a large-area gain medium in slab CO2 laser. of 240 W near-diffraction-limited beam has been attained at 12% conversion efficiency 38 cm length compact sealed-off laser head, corresponding specific extraction 14 kW m−2 discharge area.

The electronic structure of multiexcitons significantly impacts the performance nanostructures in lasing and light-emitting applications. However, these remain poorly understood due to their complexity arising from many-body physics. Standard transient-absorption photoluminescence spectroscopies are unable unambiguously distinguish effects sample inhomogeneity exciton–biexciton interactions. Here, we exploit energy time resolution two-dimensional spectroscopy access band-edge biexciton...

The hot phonon bottleneck has been under intense investigation in perovskites. In the case of perovskite nanocrystals, there may be bottlenecks as well quantum bottlenecks. While they are widely assumed to exist, evidence is growing for breaking potential both forms. Here, we perform state-resolved pump/probe spectroscopy (SRPP) and time-resolved photoluminescence (t-PL) unravel exciton relaxation dynamics model systems bulk-like 15 nm nanocrystals CsPbBr3 FAPbBr3, with FA being...

Strong confinement in semiconductor quantum dots enables them to host multiple electron–hole pairs or excitons. The excitons these materials are forced interact, resulting quantum-confined multiexcitons (MXs). MXs integral the physics of electronic properties and impact their key for applications such as gain light emission. Despite importance, structure MX has yet be fully characterized. have a complex arising from many-body effects, which is challenging both experiments theory. Here, we...

A transverse radio frequency discharge excited, carbon dioxide slab laser has been operated cw with a hybrid waveguide / confocal unstable resonator to produce an output power of 1.06 kW at 12% efficiency. The active volume 770×95×2 mm3 consists single section one cable feed.

The characteristics of coherent array beams generated by waveguide carbon dioxide laser structures have been investigated, with particular emphasis on their propagation and transformation properties. Methods beam generation are presented, measurements quality given through the use M/sup 2/ parameter. Efficient an from antisymmetric to symmetric pattern is achieved a binary phase plate, spatial filtering shown improve at expense only moderate loss total power. Coherence effects in near-field...

A two-dimensional, 39 element array of waveguide carbon dioxide lasers has produced a total CW laser power output 750 W, using RF excitation compact, close packed assembly. Thermal effects associated with close-packing in the are evaluated terms discharge wall temperature rise and cavity mirror distortion. The elements shown to have 30% derating relative single isolated channel, caused mainly by internal rise. Mirror distortion constructional errors do not degrade beam quality emission,...

The theoretical and experimental study of alpha RF discharges presented in this paper has resulted the formulation a set similarity scaling laws for diffusion-cooled discharge-excited CW waveguide CO/sub 2/ lasers. For first time, parametric dependencies voltage-current-power characteristics transverse discharge have been investigated over range excitation frequencies 100-160 MHz, gas pressures 40-100 torr interelectrode distances 1-3 mm typical laser mixture (He:N/sub 2/Co/sub 2/=3:1:1+5...

The beam errors of an 11 bar laser diode stack fitted with fast-axis collimator lenses have been corrected by a single refractive plate, produced cutting and polishing. so-called smile effect is virtually eliminated aberration greatly reduced, improving the quality each factor up to 5. corrector plate for whole ensures that radiation from all emitters parallel common axis. Beam-pointing bars reduced below 0.7 mrad.

Two-dimensional electronic spectroscopy (2DES) has recently been gaining popularity as an alternative to the more common transient absorption due combination of high frequency and time resolution 2DES. In order advance reliable analysis population dynamics optimize method, one understand numerous field matter interactions that take place at early negative time. These have historically discussed in one-dimensional coherent artifacts assigned both resonant non-resonant system responses during...

A technique for selecting a single high-order lateral mode of rf excited slab waveguide laser is described. An in-cavity grid which matches the periodicity desired mode, together with dimensions create coherent imaging by Talbot effect, have produced stable output power 155 W in high spectral purity, single-resonator mode.

Two-quantum variants of two-dimensional electronic spectroscopy (2DES) have previously been used to characterize multi-exciton interactions in molecules and semiconductor nanostructures though many implementations are limited by phasing procedures or non-resonant signals. We implement 2DES using phase-cycling simultaneously measure one-quantum two-quantum spectra colloidal CdSe quantum dots. In the pump–probe geometry, fully absorptive automatically acquired measuring sum rephasing...

The electrical features of a high power alpha-mode RF discharge at 125 MHz are investigated experimentally. An equivalent circuit description the is presented and theoretical model proposed which accounts for role near-electrode capacitive ion sheaths in stabilizing plasma region, explains increased overall stability excitation frequencies.

Self-induced transparency has been observed for the degenerate, $F=3\ensuremath{\rightarrow}4$, hyperfine component of 1.315-\ensuremath{\mu}m magnetic dipole transition atomic iodine, at high optical power levels, up to 50 MW ${\mathrm{cm}}^{\ensuremath{-}2}$. For pulse areas approaching $2\ensuremath{\pi}$, dynamics strong coherent resonant self-focusing which accompanies self-induced have studied with a streak camera provide time-dependent analysis spatial beam profile.

Metal halide perovskites have emerged as promising materials for light-emitting and photovoltaic applications over recent years. However, unlike quantum dots (QDs) where emission occurs from a quantum-confined exciton state, the nature of emitting states within these bulk nanocrystals remains ambiguous. Herein, we present time-resolved photoluminescence (t-PL) measurements on CsPbBr3 (NCs). These data reveal that NCs exhibit spectrum to average lifetime, is seen in CdSe. Notably, there an...

A large area (slab) waveguide carbon monoxide laser, excited by a transverse radio frequency discharge and cooled diffusion, has been demonstrated at electrode temperatures down to −30 °C. maximum laser power of 120 W achieved from sealed 386×2 mm an extraction efficiency 17%. Discharge scaling factors 15.5 kW m−2 have observed cw exceeding 50 using tap water cooling achieved.

We report the results of an investigation laser-material interaction processes involved in laser drilling alumina, through use enhanced peak power (2.5 kW) CO/sub 2/ and novel temporal pulse formats. Peak was varied from 30 W to 2 kW for pulses constant energy observe effect produced on scribe depth. High-speed videography hole formation has been combined with microscopic analysis investigate key processing alumina. Plasma screening observed short, high pulses, optimal scribing achieved...

An all-solid-state pulser for the excitation of repetitively pulsed gas lasers is described which uses thyristor switching followed by a ferrite core pulse transformer and four-stage compression system using DC biased magnetic switches. analysis energy losses in complex high voltage circuit made, an conversion efficiency 73% overall shown to be obtained, commercially available materials. Interfacing TEA CO2 laser discussed.