Topic
Signal beam
About: Signal beam is a research topic. Over the lifetime, 1881 publications have been published within this topic receiving 20717 citations.
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TL;DR: In this paper, the theory of two counter-propagating polarized beams interacting in a randomly birefringent fiber via the Kerr and Raman effects is developed and applied to the quantitative description of Raman polarizers in the undepleted regime.
Abstract: The theory of two counter-propagating polarized beams interacting in a randomly birefringent fiber via the Kerr and Raman effects is developed and applied to the quantitative description of Raman polarizers in the undepleted regime. Here Raman polarizers, first reported by Martinelli, are understood as Raman amplifiers operating in the regime in which an initially weak unpolarized beam is converted into an amplified fully polarized beam towards the fiber output. Three parameters are selected for the characterization of a Raman polarizer: the degree of polarization of the outcoming beam, its state of polarization, and its gain. All of these parameters represent quantities that are averaged over all random polarization states of the initially unpolarized signal beam. The presented theory is computer friendly and applicable to virtually all practically relevant situations, including the case of co-propagating beams, and in particular to the undepleted as well as the depleted regimes of the Raman polarizer.
35 citations
TL;DR: The experimental results demonstrate coherent phenomena of OPA in the quantum regime and show phase-sensitive manipulations of quantum fluctuations for quantum information processing.
Abstract: A squeezed vacuum field can be amplified or deamplified when it is injected, as the signal beam, into a phase-sensitive optical parametric amplifier (OPA) inside an optical cavity. The spectral features of the reflected quantized signal field are controlled by the relative phase between the injected squeezed vacuum field and the pump field for the OPA. The experimental results demonstrate coherent phenomena of OPA in the quantum regime and show phase-sensitive manipulations of quantum fluctuations for quantum information processing.
35 citations
TL;DR: In this paper, the interaction of laser pulses carrying orbital angular momentum (OAM) with a symmetry-broken ladder-type quantum coupling scheme involving three internal states was investigated, where a weak probe beam acts on the lower leg of the ladder scheme, while a control beam of higher intensity drives the upper leg.
Abstract: We investigate the interaction of laser pulses carrying orbital angular momentum (OAM) with a symmetry-broken ladder-type quantum coupling scheme involving three internal states. A weak probe beam acts on the lower leg of the ladder scheme, while a control beam of higher intensity drives the upper leg. In contrast to natural atoms, such a model with broken symmetry allows generating a sum-frequency signal beam between the most upper and lower quantum states, forming a cyclic closed-loop configuration of light-matter interaction. We propose situations for the efficient transfer of optical vortices to the generated signal beam via a nonlinear three-wave mixing process. It is demonstrated that the exchange process can occur both in the electromagnetically induced transparency (EIT) and the Autler-Townes splitting (ATS) regimes. The transition between the EIT and ATS conversion schemes can smoothly happen by simply tuning the knob of the control field. It is shown that the ATS regime is considerably more favorable than the EIT to achieve maximum energy conversion efficiency between light beams carrying the OAM. The results may provide an applications-based perspective to the ongoing research centered on vortex conversion-based comparisons between the ATS and EIT.
35 citations
Patent•
07 Jun 2004
TL;DR: An apparatus for recording or reading high areal density holographically stored information with high signal-to-noise ratio is described in this article, where a holographic imaging system consisting of a first numerical aperture and a first focal length and an additional optical system for filtering the signal beam is presented.
Abstract: An apparatus for recording or reading high areal density holographically stored information with high signal-to-noise ratio. The apparatus comprises a holographic imaging system for recording or reconstructing a holographic image, having a first numerical aperture and a first focal length and an additional optical system for filtering the signal beam, having a second numerical aperture and a second focal length, wherein the numerical aperture of the additional optical system is less than the numerical aperture of the holographic imaging system and/or the focal length of the additional optical system is greater than the optical length of the holographic imaging system.
35 citations
TL;DR: In this article, an analysis is made of the problem of detecting a weak light beam from a distant source in the presence of a background of much greater intensity, by the photoelectric heterodyne technique, and it is shown that the effectiveness of the method is largely independent of the intensity of the background light and of the fluctuation properties of the incident light.
Abstract: An analysis is made of the problem of detecting a weak. light beam from a distant source in the presence of a background of much greater intensity, by the photoelectric heterodyne technique. In this method the incident light is superposed on the light beam from a local laser, whose frequency can be adjusted by a feedback arrangement so as to maximize a certain “beat note” in the output of the detector. With the aid of plausible assumptions it is shown that the effectiveness of the method is largely independent of the intensity of the background light, and of the fluctuation properties of the incident light. The key parameter is the number of photoelectrons released by the signal beam in a time comparable with its coherence time.
35 citations