Topic
Spontaneous emission
About: Spontaneous emission is a research topic. Over the lifetime, 12855 publications have been published within this topic receiving 323684 citations.
Papers published on a yearly basis
Papers
More filters
••
TL;DR: In this paper, it was shown that the signal/noise ratio of a parametric amplifier and frequency converter operating under constant pumping conditions is equal to B expressed in units of hc2/λ5 = Bvac, i.e., to the number n of photons per mode in the converted radiation.
Abstract: A proposal is made to use the relationship between the spontaneous and stimulated multiphoton transitions in determination of the spectra] brightness B and the effective temperature of noncoherent light. It is shown that the signal/noise ratio M of a parametric amplifier and frequency converter operating under constant pumping conditions is equal to B expressed in units of hc2/λ5 = Bvac, i.e., to the number n of photons per mode in the converted radiation (this number is known as the degeneracy factor). The strong frequency and angular selectivity of the coherent frequency subtraction ensures a high resolution of the proposed "photon counter". Since the relationship M = n is independent of the rate of pumping, conversion efficiency, etc., such a counter may be considered as a new type of spectral brightness and radiation temperature standard. Another possible metrological application of the parametric amplifier noise arises from the simultaneity and close coupling of the directions of emission of the idler and signal photons. This feature may be used in a source emitting a known number of photons with known momenta and directions of emission; in particular, this approach should make it possible to determine the absolute quantum efficiency of a photomultiplier.
70 citations
••
TL;DR: In this article, the authors investigated the dynamics of spontaneous emission from dye molecules embedded in opal photonic crystals and measured the lifetime of Rhodamine 6G dye as a function of both optical frequency and crystal lattice parameter of the polystyrene opals.
Abstract: We have investigated the dynamics of spontaneous emission from dye molecules embedded in opal photonic crystals. Fluorescence lifetimes of Rhodamine 6G (R6G) dye were measured as a function of both optical frequency and crystal lattice parameter of the polystyrene opals. Due to the broad homogeneous line width of the dye, the observed fluorescence lifetime varies only slightly with the frequency within the dye emission spectrum. The lifetime however does change as a function of the crystal lattice parameter. Our observations agree with theoretical calculations of the local density of optical states (LDOS) in the three-dimensional photonic crystals. The experiments and theory taken together reveal that the emission lifetime is modified over frequency ranges that are broader than the homogeneous emission line width of R6G dye.
70 citations
••
TL;DR: The generation of a new quantum interference effect in spontaneous emission from a resonantly driven system of two identical two-level atoms due to the spatial variation of the laser phase at the positions of the atoms is reported.
Abstract: We report the generation of a new quantum interference effect in spontaneous emission from a resonantly driven system of two identical two-level atoms due to the spatial variation of the laser phase at the positions of the atoms. This interference affects significantly the spectral features of the emitted radiation and the quantum entanglement in the system. The interference leads to dynamic coupling of the populations and coherences in a basis, determined by the laser phase and represents a kind of vacuum mediated superexchange between the symmetric and antisymmetric states.
70 citations
••
TL;DR: This experiment extends to shorter wavelengths the operational knowledge of a linac-based SASE free-electron laser and explicitly shows the predicted exponential growth in intensity of the optical pulse as a function of length along the undulator.
Abstract: Experimental evidence for self-amplified spontaneous emission (SASE) at 530 nm is reported. The measurements were made at the low-energy undulator test line facility at the Advanced Photon Source, Argonne National Laboratory. The experimental setup and details of the experimental results are presented, as well as preliminary analysis. This experiment extends to shorter wavelengths the operational knowledge of a linac-based SASE free-electron laser and explicitly shows the predicted exponential growth in intensity of the optical pulse as a function of length along the undulator.
69 citations
••
TL;DR: An analytical model of the influence of the amplified spontaneous emission on the effective lifetime of the excited ions is developed and with this model optimized parameters for the minimization of the lifetime reduction are found.
Abstract: For the thin-disk laser the increased amplification of spontaneous emission for larger disks limits the scalability. An analytical model of the influence of the amplified spontaneous emission on the effective lifetime of the excited ions is developed and with this model optimized parameters for the minimization of the lifetime reduction are found. It is shown that output powers up to the megawatt level are achievable with a single disk, but with disk dimensions far beyond the actual technical limits. The model is also used to evaluate the limits of achievable energy.
69 citations