31,466 research outputs found
Control of lasing in fully chaotic open microcavities by tailoring the shape factor
We demonstrate experimentally that lasing in a semiconductor microstadium can
be optimized by controlling its shape. Under spatially uniform optical pumping,
the first lasing mode in a GaAs microstadium with large major-to-minor-axis
ratio usually corresponds to a high-quality scar mode consisting of several
unstable periodic orbits. Interference of waves propagating along the
constituent orbits may minimize light leakage at particular major-to-minor-axis
ratio. By making stadium of the optimum shape, we are able to maximize the mode
quality factor and align the mode frequency to the peak of the gain spectrum,
thus minimizing the lasing threshold. This work opens the door to control
chaotic microcavity lasers by tailoring the shape factor
Cosmology in Nonlinear Born-Infeld Scalar Field Theory With Negative Potentials
The cosmological evolution in Nonlinear Born-Infeld(hereafter NLBI) scalar
field theory with negative potentials was investigated. The cosmological
solutions in some important evolutive epoches were obtained. The different
evolutional behaviors between NLBI and linear(canonical) scalar field theory
have been presented. A notable characteristic is that NLBI scalar field behaves
as ordinary matter nearly the singularity while the linear scalar field behaves
as "stiff" matter. We find that in order to accommodate current observational
accelerating expanding universe the value of potential parameters and
must have an {\it upper bound}. We compare different cosmological
evolutions for different potential parameters .Comment: 18 pages, 18 figures, some references added, revised version for
Int.J.Mod.Phys.A, appeared in Int.J.Mod.Phys.
The roles of deformation and orientation in heavy-ion collisions induced by light deformed nuclei at intermediate energy
The reaction dynamics of axisymmetric deformed Mg + Mg
collisions have been investigated systematically by an isospin-dependent
quantum molecular dynamics (IDQMD) model. It is found that different
deformations and orientations result in apparently different properties of
reaction dynamics. We revealed that some observables such as nuclear stopping
power (), multiplicity of fragments, and elliptic flow are very sensitive to
the initial deformations and orientations. There exists an eccentricity scaling
of elliptic flow in central body-body collisions with different deformations.
In addition, the tip-tip and body-body configurations turn out to be two
extreme cases in central reaction dynamical process.Comment: 5 pages, 7 figures, to appear in Physical Review C (Rapid
Communication
- …