368 research outputs found
Non-critically squeezed light via spontaneous rotational symmetry breaking
We theoretically address squeezed light generation through the spontaneous
breaking of the rotational invariance occuring in a type I degenerate optical
parametric oscillator (DOPO) pumped above threshold. We show that a DOPO with
spherical mirrors, in which the signal and idler fields correspond to first
order Laguerre-Gauss modes, produces a perfectly squeezed vacuum with the shape
of a Hermite-Gauss mode, within the linearized theory. This occurs at any
pumping level above threshold, hence the phenomenon is non-critical.
Imperfections of the rotational symmetry, due e.g. to cavity anisotropy, are
shown to have a small impact, hence the result is not singular.Comment: 4 pages, 1 figure, replaced with resubmitted versio
Direct Olive Oil Analysis
El impacto práctico del análisis directo es tan innegable como
que el contribuye decisivamente a mejorar las denominadas caracterĂsticas
analĂticas relacionadas con la productividad como la
rapidez, la reducciĂłn de costes y la minimizaciĂłn de riesgos para
los analistas y el ambiente. El principal objetivo es establecer un
adecuado "bypass" a las operaciones convencionales preliminares
del proceso analĂtico. Este artĂculo ofrece una propuesta sistemática
en este contexto y resalta el gran campo de acciĂłn de las metodologĂas
directas en los análisis de rutina del aceite de oliva. Se analizan
los dos tipos principales de metodologĂas. Por una lado, se
analiza la determinación directa de los compuestos volátiles. Por el
otro, se presentan y discuten los procedimientos simples para implementar
automáticamente las operaciones preliminares del análisis
del aceite usando sistemas simples en los que la muestra se
introduce directamente con/sin una dilución simpleThe practical impact of “direct analysis” is undeniable as it
strong contributes to enhance the so-called productive analytical
features such as expeditiousness, reduction of costs and
minimisation of risks for the analysts and environment. The main
objective is to establish a reliable bypass to the conventional
preliminary operations of the analytical process. This paper offers a
systematic approach in this context and emphasises the great field
of action of direct methodologies in the routine analysis of olive oil.
Two main types of methodologies are considered. On the one hand,
the direct determination of volatile components is systematically
considered. On the other hand, simple procedures to automatically
implement the preliminary operations of the oil analysis using
simple devices in which the sample is directly introduced
with/without a simple dilution are present and discusse
Análisis directo de aceite de oliva
The practical impact of “direct analysis” is undeniable as it strong contributes to enhance the so-called productive analytical features such as expeditiousness, reduction of costs and minimisation of risks for the analysts and environment. The main objective is to establish a reliable bypass to the conventional preliminary operations of the analytical process. This paper offers a systematic approach in this context and emphasises the great field of action of direct methodologies in the routine analysis of olive oil. Two main types of methodologies are considered. On the one hand, the direct determination of volatile components is systematically considered. On the other hand, simple procedures to automatically implement the preliminary operations of the oil analysis using simple devices in which the sample is directly introduced with/without a simple dilution are present and discussed.El impacto práctico del análisis directo es tan innegable como que el contribuye decisivamente a mejorar las denominadas caracterĂsticas analĂticas relacionadas con la productividad como la rapidez, la reducciĂłn de costes y la minimizaciĂłn de riesgos para los analistas y el ambiente. El principal objetivo es establecer un adecuado "bypass" a las operaciones convencionales preliminares del proceso analĂtico. Este artĂculo ofrece una propuesta sistemática en este contexto y resalta el gran campo de acciĂłn de las metodologĂas directas en los análisis de rutina del aceite de oliva. Se analizan los dos tipos principales de metodologĂas. Por una lado, se analiza la determinaciĂłn directa de los compuestos volátiles. Por el otro, se presentan y discuten los procedimientos simples para implementar automáticamente las operaciones preliminares del análisis del aceite usando sistemas simples en los que la muestra se introduce directamente con/sin un diluciĂłn simple
Spontaneous symmetry breaking as a resource for noncritically squeezed light
In the last years we have proposed the use of the mechanism of spontaneous
symmetry breaking with the purpose of generating perfect quadrature squeezing.
Here we review previous work dealing with spatial (translational and
rotational) symmetries, both on optical parametric oscillators and four-wave
mixing cavities, as well as present new results. We then extend the phenomenon
to the polarization state of the signal field, hence introducing spontaneous
polarization symmetry breaking. Finally we propose a Jaynes-Cummings model in
which the phenomenon can be investigated at the single-photon-pair level in a
non-dissipative case, with the purpose of understanding it from a most
fundamental point of view.Comment: Review for the proceedings of SPIE Photonics Europe. 11 pages, 5
figures
Coexistence of single-mode and multi-longitudinal mode emission in the ring laser model
A homogeneously broadened unidirectonal ring laser can emit in several
longitudinal modes for large enough pump and cavity length because of Rabi
splitting induced gain. This is the so called Risken-Nummedal-Graham-Haken
(RNGH) instability. We investigate numerically the properties of the multi-mode
solution. We show that this solution can coexist with the single-mode one, and
its stability domain can extend to pump values smaller than the critical pump
of the RNGH instability. Morevoer, we show that the multi-mode solution for
large pump values is affected by two different instabilities: a pitchfork
bifurcation, which preserves phase-locking, and a Hopf bifurcation, which
destroys it.Comment: 14 pages, 7 figure
Theory of quantum fluctuations of optical dissipative structures and its application to the squeezing properties of bright cavity solitons
We present a method for the study of quantum fluctuations of dissipative
structures forming in nonlinear optical cavities, which we illustrate in the
case of a degenerate, type I optical parametric oscillator. The method consists
in (i) taking into account explicitly, through a collective variable
description, the drift of the dissipative structure caused by the quantum
noise, and (ii) expanding the remaining -internal- fluctuations in the
biorthonormal basis associated to the linear operator governing the evolution
of fluctuations in the linearized Langevin equations. We obtain general
expressions for the squeezing and intensity fluctuations spectra. Then we
theoretically study the squeezing properties of a special dissipative
structure, namely, the bright cavity soliton. After reviewing our previous
result that in the linear approximation there is a perfectly squeezed mode
irrespectively of the values of the system parameters, we consider squeezing at
the bifurcation points, and the squeezing detection with a plane--wave local
oscillator field, taking also into account the effect of the detector size on
the level of detectable squeezing.Comment: 10 figure
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