Showing papers on "Signal beam published in 1984"
TL;DR: In this article, phase conjugation that is due to degenerate forward four-wave mixing was studied both theoretically and experimentally and the numerical solution of the nonstationary problem was presented, revealing the transient oscillations of the PC-beam intensity with maxima many times exceeding the saturation value.
Abstract: Phase conjugation (PC) that is due to degenerate forward four-wave mixing is studied both theoretically and experimentally. Similarly to backward four-wave mixing, the limiting efficiency of this process corresponds to the total energy transfer from each pump wave into the signal and conjugate waves, although in this case the Yariv oscillations do not occur. The numerical solution of the nonstationary problem is presented, revealing the transient oscillations of the PC-beam intensity with maxima many times exceeding the saturation value. PC of Q-switched and free-oscillating solid-state laser radiation is obtained by using the thermal nonlinearity of absorbing solutions. PC of cw laser radiation is obtained in a LiNbO3 crystal, the PC-beam intensity being six times larger than the initial intensity of the signal beam. The self-compensation of nonlinear phase distortions of the recording medium is demonstrated.
28 citations
TL;DR: In this paper, degenerate four-wave mixing was observed in alexandrite crystals (BeAl2O4:Cr3+), and the signal beam efficiency and decay rate were measured as functions of pump beam-crossing angle, wave-length, and power.
Abstract: : Degenerate four-wave mixing was observed in alexandrite crystals (BeAl2O4:Cr3+), and the signal beam efficiency and decay rate were measured as functions of pump beam-crossing angle, wave-length, and power. The results are consistent with scattering from excited-state population gratings related to the difference in despersion of the Cr3+ ions in the ground and metastable states. These gratings can be selectively established with Cr3+ ions in the inversion or mirror sites depending on excitattion wavelength. Strong scattering occurs only for pump beams polarized parallel to the b direction of the crystal. Originator- supplied keywords include: Lasers, Alexandrite, Non-Linear Optics.
18 citations
Patent•
17 Feb 1984TL;DR: In this article, an apparatus is described for measuring spatial phase difference between a signal beam and a reference beam in substantially real-time, where the signal and reference beams are coherent beams of optical radiation superimposed upon each other and having orthogonal polarization states with respect to each other.
Abstract: An apparatus is described for measuring spatial phase difference between a signal beam and a reference beam in substantially real time, where the signal and reference beams are coherent beams of optical radiation superimposed upon each other and having orthogonal polarization states with respect to each other.
17 citations
Patent•
19 Mar 1984
TL;DR: In this paper, the authors proposed to eliminate an isolator by imparting reference beam and signal beam to a photoelectric converter while reflecting both beams by the polarizing beam splitter.
Abstract: PURPOSE:To eliminate an isolator because laser beam is not passed through a polarizing beam splitter and is not fed back to a laser beam source and to enable the use of semiconductor laser and miniaturization, by imparting reference beam and signal beam to a photoelectric converter while reflecting both beams by the polarizing beam splitter CONSTITUTION:When an object 6 to be measured is moved in a region to be measured at a certain speed as shown by the drawing, emitted laser beam is again applied to a 1/4 wavelength plate 12 by the object 6 Because reflected laser beam (signal beam) receives doppler shift DELTAf proportional to the speed of the object 6, the frequency of the signal beam comes to fo+DELTAf Reference beam and signal beam are propagated to reverse directions in an optical fiber 11 but the polarizing direction of laser beam is held and condensed by a lens 4 to be again imparted to a polarizing beam splitter 3 Heterodyne detection due to the beam beats of reference beam and signal beam is performed in a photoelectric converter 7 and an electric signal with frequency of DELTAf The frequency DELTAf is measured by a frequency measuring instrument 8 and speed information can be obtained in a signal treating part 9
5 citations