Europium-doped strontium and barium iodide are found to be readily growable by the Bridgman method and to produce high scintillation light yields. Sr12(Eu) emits into the Eu2+ band, centered at 435 nm, with a decay time of 1.2 ps and a light yield of -90 000 photons/MeV. It offers energy resolution better than 4% full width at half maximum at 662 keV, and exhibits excellent light yield proportionality. BaIz(Eu) produces >30 000 photons/MeV into the Eu2+ band at 420 nm (< 1 ps decay). An additional broad impurity-mediated recombination band is present at 550 nm (>3 ps decay), unless high-purity feedstock is used.

We report two cw, singly resonant optical parametric oscillator (OPO) configurations based on periodically poled lithium niobate that result in significantly higher efficiency and output power than in previous studies. Using four-mirror OPO cavities and pumping with a 1.064-microm Nd:YAG laser, we observe 93% pump depletion and obtain ~86% of the converted pump photons as useful idler output. The single-beam, in-the-bucket idler output power of 3.55 W at 3.25 microm corresponds to ~80% of quantum-limited performance. We measure and compare the amplitude noise and spectral bandwidth of the two configurations. We also demonstrate >1 W of tunable cw output over the 3.3-3.9-microm spectral range.

We report a continuous-wave singly resonant optical parametric oscillator (OPO) based on periodically poled lithium niobate. The simple, two-mirror OPO, pumped by a 1.064-microm Nd:YAG laser, had a 2.6-4.5-W threshold and an output of >1.2 W at 3.3 microm and was tuned over 1.45-1.62 microm (signal) and 3.98-3.11 microm (idler). The noise characteristics and the spectral properties of the device are described.

No abstract

No abstract

No abstract

We report high efficiency luminescence with a manganese-doped aluminum nitride redemitting phosphor under 254 nm excitation, as well as its excellent lumen maintenance in fluorescent lamp conditions, making it a candidate replacement for the widely deployed europium-doped yttria red phosphor. Solid-state reaction of aluminum nitride powders with manganese metal at 1900 °C, 10 atm N 2 in a reducing environment results in nitrogen deficiency, as revealed diffuse reflectance spectra. When these powders are subsequently annealed in flowing nitrogen at 1650 °C, higher nitrogen content is recovered, resulting in white powders. Silicon was added to samples as an oxygen getter to improve emission efficiency. NEXAFS spectra and DFT calculations indicate that the Mn dopant is divalent. From DFT calculations, the UV absorption band is proposed to be due to an aluminum vacancy coupled with oxygen impurity dopants, and Mn 2+ is assumed to be closely associated with this site. In contrast with some previous reports, we find that the highest quantum efficiency with 254 nm excitation (Q.E. = 0.86±0.14) is obtained in aluminum nitride with a low manganese doping level of 0.06 mol%. The principal Mn 2+ decay of 1.25 ms is assigned to non-interacting Mn sites, while additional components in the microsecond range appear with higher Mn doping, consistent with Mn clustering and resultant exchange coupling. Slower components are present in samples with low Mn doping, as well as strong afterglow, assigned to trapping on shallow traps followed by detrapping and subsequent trapping on Mn.

We demonstrate temporal imaging for the measurement and characterization of optical arbitrary waveforms and events. The system measures single-shot 200 ps frames at a rate of 104 MHz, where each frame is time magnified by a factor of -42.4x. Impulse response tests show that the system enables 783 fs resolution when placed at the front end of a 20 GHz oscilloscope. Modulated pulse trains characterize the system's impulse response, jitter, and frame-to-frame variation.