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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.


Papers
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Journal ArticleDOI
TL;DR: Low-power all-optical switching with pharaonis phoborhodopsin (ppR) protein is demonstrated based on nonlinear excited-state absorption at different wavelengths and it is shown that the switching characteristics at 560 and 600 nm, respectively, can exhibit negative to positive switching.
Abstract: Low-power all-optical switching with pharaonis phoborhodopsin (ppR) protein is demonstrated based on nonlinear excited-state absorption at different wavelengths. A modulating pulsed 532-nm laser beam is shown to switch the transmission of a continuous-wave signal light beam at: 1) 390 nm; 2) 500 nm; 3) 560 nm; and 4) 600 nm, respectively. Simulations based on the rate equation approach considering all seven states in the ppR photocycle are in good agreement with experimental results. It is shown that the switching characteristics at 560 and 600 nm, respectively, can exhibit negative to positive switching. The switching characteristics at 500 nm can be inverted by increasing the signal beam intensity. The profile of switched signal beam is also sensitive to the modulating pulse frequency and signal beam intensity and wavelength. The switching characteristics are also shown to be sensitive to the lifetimes of ppRM and ppRO intermediates. The results show the applicability of ppR as a low-power wavelength tunable all-optical switch

27 citations

Patent
12 Feb 1982
Abstract: A stabilizer for the relative mirror separation and inclination in a Michelson (two beam) or a Fabry-Perot (multiple beam) interferometer that generates at least three reference beams and in one embodiment an optional monitor beam. The reference beams are disposed substantially around the interferometer signal beam and are directed through the interferometer. The resultant intensity from the interference within each reference beam (transmission) is detected and compared to a fixed reference, in one embodiment the monitor beam. Based upon the ratio of reference intensity to fixed reference, the mirror position is controlled to maintain a constant spacing with respect to the wavelength of the reference source. A stepped mirror surface in the interferometer is used in one embodiment and provides a constant difference between effective mirror spacing encountered by a signal beam and the spacing encountered by reference beams. A servo system is provided to adjust mirror spacing to maintain a constant transmission ratio for each of the reference beams in response to distortion in the interferometer or changes in reference wavelength. A method of stabilizing a Michelson and a Fabry-Perot interferometer utilizing reference beams derived from an independent reference source of nearly monochromatic radiation is also disclosed.

26 citations

PatentDOI
TL;DR: In this paper, a wide-area acousto-optic hydrophone which uses signal and reference laser beams together with interferometric methods for detecting underwater acoustic signals is presented.
Abstract: A wide-area acousto-optic hydrophone which uses signal and reference laser beams together with interferometric methods for detecting underwater acoustic signals. The signal beam is distributed across the wide sensing area of the hydrophone using beam folding techniques while being directly transmitted through a sensing chamber filled with an optically transparent bulk material, the refractive index of which varies with the incident acoustic pressure thereby modulating the signal beam. Concurrently, a reference beam of equal length and folded in an identical pattern is directly passed through an adjacent chamber filled with the same bulk material. A microhole joins the two chambers, to expose the reference beam to the same static pressure and temperature fluctuations as the signal beam thus serving as a low pass filter. The modulated signal beam and the unmodulated reference beam are then combined and superimposed on the surface of a photodetector, the output of which is proportional to the phase shifts produced by the incident acoustic signals.

26 citations

Journal ArticleDOI
TL;DR: In a doubly resonant degenerate optical parametric oscillator below threshold the signal beam can be trapped in the form of stable bright temporal or spatial solitons, and how to excite them is discussed.
Abstract: In a doubly resonant degenerate optical parametric oscillator below threshold the signal beam can be trapped in the form of stable bright temporal or spatial solitons. We characterize these soliton families and discuss how to excite them.

26 citations

Journal ArticleDOI
TL;DR: In this article, a femtosecond green-pumped optical parametric oscillator (OPO) based on lithium triborate was used for coherent anti-Stokes Raman scattering spectroscopy.
Abstract: We present detailed investigations of a femtosecond green-pumped optical parametric oscillator (OPO) based on lithium triborate. As pump source, a frequency-doubled Yb-fiber laser-amplifier system is used. The OPO generates signal pulses tunable over a spectral range from 780 to 940 nm and idler pulses tunable from 1630 to 1190 nm. More than 250 mW are generated in the signal beam and more than 300 mW in the idler beam. Without dispersion compensation chirped signal pulses with a pulse duration between 100 and 250 fs are measured. Using this system for coherent anti-Stokes Raman scattering spectroscopy, vibrational resonances between 1110 and 6760 cm−1 can be excited. Due to the chirped pulses, a spectral resolution of 100 cm−1 is achieved, which is 2.5 times higher compared to an excitation with time-bandwidth limited pulses.

26 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202310
202215
202131
202040
201929
201844