Topic
Spontaneous emission
About: Spontaneous emission is a research topic. Over the lifetime, 12855 publications have been published within this topic receiving 323684 citations.
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TL;DR: In this paper, when dye-solution filled in air-holes of a 2D photonic lattice was optically-pumped, laser action without external mirrors was found to occur at a specific wavelength corresponding to a flat band dispersion in a high-symmetry direction of the 2D lattice plane; a small group-velocity is responsible for the lasing.
Abstract: We report on observation of laser action unique to a two-dimensional (2D) photonic lattice. When dye-solution filled in air-holes of a 2D lattice was optically-pumped, laser action without external mirrors is found to occur at a specific wavelength corresponding to a flat band-dispersion in a high-symmetry direction of the 2D lattice plane; a small group-velocity is responsible for the lasing. On further increasing the pump-fluence, another laser action is also found to occur around a peak wavelength of the spontaneous emission spectrum. This lasing is interpreted of as arising from the so-called uncoupled modes possessing a high Q-value.
67 citations
TL;DR: In this article, the authors analyzed the current injection efficiency of separate confinement heterostructure (SCH) quantum film lasers and showed that the injection efficiency changes stepwise with the active layer thickness and is larger for lower injected carrier density and deeper quantum well.
Abstract: Current injection efficiency, i.e. the proportion of current into the active region to total current, is analyzed for separate confinement heterostructure (SCH) quantum film lasers. It is shown that the current injection efficiency changes stepwise with the active layer thickness. and is larger for lower injected carrier density and deeper quantum well. Comparison is made between step-, parabolic-GRIN-, and linear-GRIN-SCH structures. The efficiency of linear-GRIN-SCH is the highest for the same well depth. Threshold current density is discussed for these SCH structures, taking into account the current injection efficiency and the optical loss due to the carrier leakage to the optical confinement layers. >
67 citations
TL;DR: In this paper, an analysis of the pulse-to-pulse timing jitter in an actively mode-locked laser is presented, which includes spontaneous emission noise, mode-locker driver phase noise, and cavity length detuning.
Abstract: An analysis of the pulse-to-pulse timing jitter in an actively mode-locked laser is presented. The model includes spontaneous emission noise, mode-locker driver phase noise, and cavity length detuning. Analytical expressions for the laser pulse train phase noise spectrum, the intensity power spectrum, and the RMS timing jitter are given. The timing fluctuations are characterized by a time constant proportional to the cavity round-trip time times the number of locked modes squared divided by the modulation depth. The contribution from the mode-locker driver phase noise will dominate unless high-stability RF sources are used. The residual timing jitter due to spontaneous emission noise is very sensitive to cavity detuning. >
67 citations
TL;DR: The effects of spontaneous emission and intense fields on the dipole-dipole interaction-induced two-photon resonance is studied using density-matrix methods and the presence of an intense field is shown to result in a significant enhancement of the two- photon resonance.
Abstract: The two-photon absorption by a pair of two-level atoms interacting with an incident field is examined. If the laser field is weak, then the existence of the dipole-dipole interaction-induced two-photon resonance follows from the higher-order Fermi golden rule. The effects of spontaneous emission and intense fields on the dipole-dipole interaction-induced two-photon resonance is studied using density-matrix methods. The presence of an intense field is shown to result in a significant enhancement of the two-photon resonance. Numerical results for the probability of simultaneous excitation of two atoms, for the atomic correlations, and for the radiated field intensity are presented.
67 citations
TL;DR: In this paper, a review of exo-electron emission phenomena is presented and the question of nomenclature is discussed, and the importance of crystal imperfections is brought out by the parallelism between luminescence and exo electron emission, which depends only on the presence of donor centres, but not on the activator centres necessary for the former to occur.
Abstract: "Exo-electron" emission phenomena are reviewed. Kramer's original hypothesis that exothermal processes are the cause of the effect is no longer considered valid and it is now widely accepted that particularities of the crystal lattice, such as crystal imperfections are present in surfaces showing electron emission after mechanical deformation, X- or ultra-violet irradiation, electron bombardment, etc. Apparently spontaneous emission during phase changes of metals requires the presence of surface films. Oxygen must be present for emission to occur after the mechanical deformation of metals and photo-electric emission measurements suggest that certain surface oxides then contain negative-ion vacancies (F-centres). The emission from ionic materials, such as alkali halides, depends on the presence of colour centres. The importance of crystal imperfections is brought out by the parallelism between luminescence and exo-electron emission. The latter depends only on the presence of donor-centres, but not on the activator centres necessary for the former to occur. Various applications of exo-electron phenomena and the question of nomenclature are discussed.
67 citations