5,700 research outputs found
Enhanced conversion efficiency for harmonic generation with double resonance
Conversion efficiency for cw harmonic generation is calculated for the situation in which both fundamental and harmonic waves are resonant. Compared with the situation of a singly resonant cavity at the fundamental, the doubly resonant geometry can lead to an increase of the effective nonlinear coefficient. High conversion efficiency can thus be achieved with nonlinear crystals of relatively low nonlinear coefficient. and with modest pump power for the fundamental input
Spin correlated interferometry for polarized and unpolarized photons on a beam splitter
Spin interferometry of the 4th order for independent polarized as well as
unpolarized photons arriving simultaneously at a beam splitter and exhibiting
spin correlation while leaving it, is formulated and discussed in the quantum
approach. Beam splitter is recognized as a source of genuine singlet photon
states. Also, typical nonclassical beating between photons taking part in the
interference of the 4th order is given a polarization dependent explanation.Comment: RevTeX, 19 pages, 1 ps figure, author web page at
http://m3k.grad.hr/pavici
Comparisons and Applications of Four Independent Numerical Approaches for Linear Gyrokinetic Drift Modes
To help reveal the complete picture of linear kinetic drift modes, four
independent numerical approaches, based on integral equation, Euler initial
value simulation, Euler matrix eigenvalue solution and Lagrangian particle
simulation, respectively, are used to solve the linear gyrokinetic
electrostatic drift modes equation in Z-pinch with slab simplification and in
tokamak with ballooning space coordinate. We identify that these approaches can
yield the same solution with the difference smaller than 1\%, and the
discrepancies mainly come from the numerical convergence, which is the first
detailed benchmark of four independent numerical approaches for gyrokinetic
linear drift modes. Using these approaches, we find that the entropy mode and
interchange mode are on the same branch in Z-pinch, and the entropy mode can
have both electron and ion branches. And, at strong gradient, more than one
eigenstate of the ion temperature gradient mode (ITG) can be unstable and the
most unstable one can be on non-ground eigenstates. The propagation of ITGs
from ion to electron diamagnetic direction at strong gradient is also observed,
which implies that the propagation direction is not a decisive criterion for
the experimental diagnosis of turbulent mode at the edge plasmas.Comment: 12 pages, 10 figures, accept by Physics of Plasma
Mode-Locked Two-Photon States
The concept of mode locking in laser is applied to a two-photon state with
frequency entanglement. Cavity enhanced parametric down-conversion is found to
produce exactly such a state. The mode-locked two-photon state exhibits a
comb-like correlation function. An unbalanced Hong-Ou-Mandel type
interferometer is used to measure the correlation function. A revival of the
typical interference dip is observed. We will discuss schemes for engineering
of quantum states in time domain.Comment: 4 pages, 5 figure
85% efficiency for cw frequency doubling from 1.08 to 0.54 ÎĽm
Conversion efficiency of 85% has been achieved in cw second-harmonic generation from 1.08 to 0.54 ÎĽm with a potassium titanyl phosphate crystal inside an external ring cavity. An absolute comparison between the experimental data and a simple theory is made and shows good agreement
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