40,803 research outputs found
Coupled resonators employing phase-conjugating and ordinary mirrors
We calculate the oscillation conditions and the eigen-frequencies for phase-conjugating-resonator-normal-resonator coupled optical systems. With an eye toward applications to interferometry, we choose specific examples for which it is shown that the conditions for oscillation and the eigenfrequencies depend on the normal-resonator path length. The examples include both linear displacement and rotation sensing (Sagnac) resonant interferometers. Our results suggest that if the distortion-correcting and self-aligning properties of the phase-conjugating resonator are retained in the more complicated system, then these hybrid resonators may offer some advantages over their conventional counterparts
Alignment of resonant optical cavities
When an input Gaussian beam is improperly aligned and mode-matched to a stable optical resonator, the electric field in the resonator couples to off-axis spatial eigenmodes. We show that a translation of the input axis or a mismatch of the beam waist to the resonator waist size causes a coupling of off-axis modes which is inphase with the input field. On the other hand, a tilt of the input beam or a mismatch of the beam waist position to cavity waist position couples to these modes in quadrature phase. We also propose a method to measure these coupling coefficients and thereby provide a means to align and mode-match a resonant optical cavity in real time
Simplified landscapes for optimization of shaken lattice interferometry
Motivated by recent results using shaken optical lattices to perform atom
interferometry, we explore splitting of an atom cloud trapped in a
phase-modulated ("shaken") optical lattice. Using a simple analytic model we
are able to show that we can obtain the simplest case of splitting via single-frequency shaking. This is confirmed both
via simulation and experiment. Furthermore, we are able to split with a
relative phase between the two split arms of or depending on
our shaking frequency. Addressing higher-order splitting, we determine that
splitting is sufficient to be able to accelerate the
atoms in counter-propagating lattices. Finally, we show that we can use a
genetic algorithm to optimize and splitting to within by restricting our
optimization to the resonance frequencies corresponding to single- and
two-photon transitions between Bloch bands
Effects of hydrolysis ageing on the performance and dimensional stability of glass-fiber reinforced polyamide 66
Results of an in-depth study of hydrolysis testing on the mechanical performance, weight change, and dimensional stability of injection moulded glass-fiber reinforced polyamide 66 automotive composites are presented. Composite and resin samples have been characterised after conditioning in water-glycol mixtures at 70°C, 120°C and 150°C for a range of times up to 1000 hours. The results reveal that hydrothermal ageing results in significant changes in the mechanical performance, weight, and dimensions of these materials. Mechanical performance after conditioning at different temperatures could be superimposed when considered as a function of the level of fluid absorbed by the composite matrix
Signature of a universal statistical description for drift-wave plasma turbulence
This Letter provides a theoretical interpretation of numerically generated
probability density functions (PDFs) of intermittent plasma transport events.
Specifically, nonlinear gyrokinetic simulations of ion-temperature-gradient
turbulence produce time series of heat flux which exhibit manifestly
non-Gaussian PDFs with enhanced tails. It is demonstrated that, after the
removal of autocorrelations, the numerical PDFs can be matched with predictions
from a fluid theoretical setup, based on the instanton method. This result
points to a universality in the modeling of intermittent stochastic process,
offering predictive capability.Comment: 4 pages, 5 figure
Transistor-Like Behavior of a Bose-Einstein Condensate in a Triple Well Potential
In the last several years considerable efforts have been devoted to
developing Bose-Einstein Condensate (BEC)-based devices for applications such
as fundamental research, precision measurements and integrated atom optics.
Such devices capable of complex functionality can be designed from simpler
building blocks as is done in microelectronics. One of the most important
components of microelectronics is a transistor. We demonstrate that
Bose-Einstein condensate in a three well potential structure where the
tunneling of atoms between two wells is controlled by the population in the
third, shows behavior similar to that of an electronic field effect transistor.
Namely, it exhibits switching and both absolute and differential gain. The role
of quantum fluctuations is analyzed, estimates of switching time and parameters
for the potential are presented.Comment: 12 pages, 12 figure
Mirror reflectometer based on optical cavity decay time
Described is a reflectometer capable of making reflectivity measurements of low-loss highly reflecting mirror coatings and transmission measurements of low-loss antireflection coatings. The technique directly measures the intensity decay time of an optical cavity comprised of low-loss elements. We develop the theoretical framework for the device and discuss in what conditions and to what extent the decay time represents a true measure of mirror reflectivity. Current apparatus provides a decay time resolution of 10 nsec and has demonstrated a cavity total loss resolution of 5 ppm
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