An air-bridged, 120-nm-thick semiconductor slab with a two-dimensional (2D) square array of through holes on a 480 nm pitch (Λ) was fabricated using selective wet etching techniques. The second order photonic resonances of the structure were studied by comparing broadband optical scattering data with numerical solutions of Maxwell’s equations. Features observed in these spectra over a 1200 cm−1 range, near 9500 cm−1, indicate that the 2D texture splits the energy degeneracy of slab modes with propagation constants {±2π/Λ,0} and {0,±2π/Λ} by as much as 14%.
Comtinuous-wave ͑cw͒ operation of organometallic vapor phase epitaxy-grown In 0.4 Ga 0.6 As 0.995 N 0.005 quantum well ͑QW͒ lasers has been realized, at a room-temperature near-threshold emission wavelength of 1.295 m, with a threshold-current density of 220 A/cm 2 for 2000 m cavity-length (L cav) devices. A threshold current density of only 615 A/cm 2 was achieved for cw operation at a temperature of 100°C, with an emission wavelength of 1.331 m. A maximum cw-output power of 1.8 W was obtained for InGaAsN QW lasers with cavity lengths of 1000 and 2000 m, at a heat-sink temperature of 20°C.
We report diode-pumped Er3+:Y2O3 ceramic laser with ~14 W of true CW output at ~2.7 μm. This presents nearly ten-fold power increase with respect to previous best result with this laser material. We also believe this to be the highest power ever reported from Er3+ -doped bulk crystalline laser operating in a ~3-μm wavelength range. Power-scaled performance of 974-nm pumped Er3+:Y2O3 laser was achieved with the slope efficiency of ~26%.
We have demonstrated a monolithic cladding-pumped ytterbium-doped single all-fiber laser oscillator generating 1 kW of CW signal power at 1080 nm with 71% slope efficiency and near diffraction-limited beam quality. Fiber components were highly integrated on "spliceless" passive fibers to promote laser efficiency and alleviate non-linear effects. The laser was pumped through a 7:1 pump combiner with seven 200-W 91x nm fiber-pigtailed wavelength-beam-combined diode-stack modules. The signal power of such a single all-fiber laser oscillator showed no evidence of roll-over, and the highest output was limited only by available pump power.
The radiative emission of strongly driven, two-level-like barium atoms into the modes of a confocal optical cavity is studied as a function of barium density. As the barium density is increased, the spatial profile, intensity, and spectrum of light emitted out the ends of the confocal cavity display dramatic changes indicative of a transition from Auorescence to lasing. In this novel two-level system, laser action can be explained in terms of an inversion between the dressed atom-field states or in terms of a type of stimulated hyper-Raman scattering in which atoms lase from the ground to the excited atomic state. A simple dressed-atom rate-equation analysis of this two-level-atom laser is presented. It is pointed out that this same system may provide a means of realizing two-photon-like laser action.
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