Signal beam

About: Signal beam is a research topic. Over the lifetime, 1881 publications have been published within this topic receiving 20717 citations.

Recording and reproducing device, recording and reproducing method, recording device, recording method, reproducing device and reproducing method

Abstract: A recording technique for performing data recording onto a hologram recording medium in accordance with information on phases by performing spatial light phase modulation as spatial light modulation corresponding to recording data, and a reproducing technique for reproducing recorded data by properly reading information on phases recorded as described above are suggested. A signal beam having a phase modulation pattern provided thereto corresponding to recording data and a reference beam having a specific phase modulation pattern provided thereto are applied to the hologram recording medium. Thus, recording data can be recorded onto the hologram recording medium in accordance with information on phases. In addition, at the time of reproduction, a reference beam and a DC beam having the entire phase whose phase difference with respect to a reference phase within the reference beam is π/2 are applied to the hologram recording medium. By providing a phase difference based on π/2 as described above, the phase of a reproduction beam obtained from the hologram recording medium in accordance with application of the reference beam and the phase of the DC beam can be set to be the same. Thus, the DC beam can be added as a component of an amplitude of "1" to the reproduction beam. By reading the reproduction beam to which the DC beam is added as described above, recorded information on phases can be correctly read, and recorded data can be reproduced in accordance with the phase information.

Method for measuring thin metal films

Abstract: A method and system for measuring properties of a sample are disclosed. At least one source of excitation radiation is used to irradiate the sample's surface. This excites multiple acoustic modes within the sample. A probe source of radiation diffracts off the acoustic modes to generate a signal beam. The signal beam is detected and analyzed to yields a signal waveform, from which a Fourier Transform spectrum is derived. The Fourier Transform spectrum features frequencies corresponding to the multiple acoustic modes. Analysis of the spectrum yields measurements of the sample's properties.

Systems and methods for quantum illumination detection for optical communications and target detection

Abstract: A detection system including a receiver, a transmitter, and a processor for stealthy target detection or optical communications is described. Optical communications may be spread spectrum encoded communications over a bright background communication channel. The transmitter includes a quantum frequency entanglement source for outputting a signal beam and an idler beam, and transmission optics for directing the signal beam towards a remote surface. Photons in the idler beam are quantum-mechanically entangled in frequency with photons the signal beam. The transmitter includes a first spectrometer for measuring a frequency band associated with photons in the idler beam. The receiver includes a second spectrometer for identifying the frequency band associated with the photons in the received return beam. The system includes a processor configured to process the output of the spectrometers to determine the presence of a target in a target region or a message encoded in the received return beam.

Self-pumped phase conjugation induced by an incoherent beam

Abstract: An incoherent beam was used to induce the self-pumped phase-conjugate output in a (BaSr) TiO3 crystal. It was found that, in terms of the alteration of the signal-beam parameters, the induced self-pumped phase-conjugate output could be eliminated or maintained after the incoherent beam was removed. The observed effects were attributed to the local modification of the fanning geometry of the signal beam.

Frequency conversion of an entangled state

Abstract: The quantum characteristics of sum-frequency process in an optical cavity with an input signal optical beam, which is a half of entangled optical beams, are analyzed. The calculated results show that the quantum properties of the signal beam can be maintained after its frequency is conversed during the intracavity nonlinear optical interaction. The frequency-conversed output signal beam is still in an entangled state with the retained other half of the initial entangled beams. The resultant quantum correlation spectra and the parametric dependences of the correlations on the initial squeezing factor, the optical losses and the pump power of the sum-frequency cavity are calculated. The proposed system for the frequency conversion of the entangled state can be used in quantum communication network and the calculated results can provide direct references for the design of experimental systems.