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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 article, the performance of a nonlinear lossless polarizer (NLP) was investigated in terms of the instantaneous degree of polarization, which is a natural extension of the conventional notion of the degree of polarization appropriate for CW beams to the case of pulses whose SOP is not constant across the pulse.
Abstract: We study the performance of a nonlinear lossless polarizer (NLP), the device that transforms an input arbitrary state of polarization (SOP) of a signal beam into one and the same SOP toward the output and, unlike conventional passive polarizers, performs this transformation without polarization-dependent losses. The operation principle of this device is based on the nonlinear rotation of the SOP of the strong signal beam under the interaction with a copropagating strong pump beam in a Kerr medium, which in our case is a telecom fiber. We quantify the performance of this NLP by introducing the notion of instantaneous degree of polarization, which is a natural extension of the conventional notion of the degree of polarization appropriate for CW beams to the case of pulses whose SOP is not constant across the pulse. We pay particular attention to the regime when signal and pump beams experience a walk-off in the dispersive medium. In particular, we demonstrate that a signal pulse experiences much stronger repolarization when the walk-off effect is present as compared with the case of no walk-off. We also study the degradation of the efficiency of the NLP in the presence of polarization mode dispersion.
17 citations
Patent•
10 Feb 1986TL;DR: In this paper, a nonlinear optical receiver includes a source of coherent light of frequency ω for illuminating a spatial region, which is reflected from objects within the spatial region constitutes a signal beam.
Abstract: A nonlinear optical receiver includes a source of coherent light of frequency ω for illuminating a spatial region. The portion of the source light which is reflected from objects within the spatial region constitutes a signal beam. A reference beam of coherent light of frequency ω is also provided. A photorefractive element receives the signal and reference beams and amplifies the signal beam by two-wave mixing. The receiver may include a first polarizer, having a first polarization direction, placed between a cubic photorefractive element and the signal and reference beams, and a second polarizer, having a second polarization direction perpendicular to the first polarization direction, placed so that the amplified signal beam must pass therethrough. A frequency shifting element, such as a Bragg cell modulator, is used to change the frequency of the reference beam. pa A first laser may provide both the source of coherent light and the reference beam of coherent light, or a first laser may provide the source of coherent light while a second laser provides the reference beam of coherent light. The photorefractive element may be a cubic photorefractive crystal or a nonlinear optic material. A two dimensional focal plane array may be added for detecting the amplified signal beam.
17 citations
TL;DR: In this article, the experimental results of measurements of spatial solitons (nematicons) in chiral nematic liquid crystalline film were presented for the first time.
Abstract: In this work we present for the first time experimental results of measurements of spatial solitons (nematicons) in chiral nematic liquid crystalline film. We measured the propagation of light beam at the distance of a few millimeters and the nonlinear self-focusing was observed for a light power of order of a few tenths of milliwats. Additional, in a waveguide induced by the nematicon, other low-power light beam (signal beam) with different wavelength was trapped. There were also observed the changes of the nematicon direction by changing the position across the nematics layer. The experimental results are in a good agreement with theoretical predictions.
17 citations
Patent•
09 Jun 1971
TL;DR: In this article, a method and apparatus for recording intelligence on a moving sheet such as a light sensitive strip is described, where the data is modulated into a coherent light reference or a signal beam of a holographic recording system while one of the beams is altered in angle for each pass across the recording strip to record a series of holograms, each adjacent series on the strip having a spatial frequency different from the next wherein overlap will not interfere with readout which isolates each frequency in turn.
Abstract: A method and apparatus for recording intelligence on a moving sheet such as a light sensitive strip. The data is modulated into a coherent light reference or a signal beam of a holographic recording system while one of the beams is altered in angle for each pass across the recording strip to record a series of holograms, each adjacent series on the strip having a spatial frequency different from the next wherein overlap will not interfere with readout which isolates each frequency in turn.
17 citations
TL;DR: In this paper, the authors define the time-invariant detection scheme which yields the largest average signal-to-noise ratio in the heterodyne detection of a randomly distorted optical signal.
Abstract: This paper defines the time-invariant detection scheme which yields the largest average signal-to-noise ratio in the heterodyne detection of a randomly distorted optical signal. It is shown that the detection scheme may be realized by properly shaping both the isophase surface and the irradiance distribution of the local-oscillator beam. Applied to the case of an atmospherically distorted optical plane wave it is shown that although the optimum local-oscillator beam differs significantly from a plane wave, the increase of average signal-to-noise ratio, over the plane-wave case as reported by Fried, is negligible (less than 10%).
17 citations