Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Quantum Electronics

Phase conjugation of a speckle-inhomogeneous beam by an Nd glass oscillator based on four-wave mixing with feedback

A V Kirsanov, Vladimir V. Yarovoy

Published Mar 31, 1997• 6 citations
Publisher

Abstract

A study is reported of a system, making use of four-wave mixing with feedback (FWMF), for high-quality phase conjugation of speckle-inhomogeneous radiation. The system includes a hologram formed on the basis of nonlinearity of gain saturation. A theoretical analysis is made of selective capabilities of a 'short' hologram, whose length is less than the longitudinal correlation lengths of the 'write' waves used to form it. The statistical-average values of the parameters of modes in an FWMF cavity are determined. The experimental results obtained for a neodymium glass system show that the fidelity of phase conjugation of speckle beams with a divergence (5 — 25) θ diffr is 80%. The maximum energy of the phase-conjugated component is 0.35 J and the maximum energy reflection coefficient of an FWMF mirror is 20.

DOI
10.1070/qe1997v027n03abeh000910

Related papers

Selection of a phase-conjugate wave in an oscillator based on a four-wave interaction with feedback in an extended nonlinear medium

Alexander A. Betin, A V Kirsanov

A quasi-optical approximation without allowance for beam spreading over its envelope is used to show that selection of a conjugate wave occurs in a volume hologram whose dimensions are greater than the longitudinal correlation length of the fields forming the hologram. The condition under which the signal power exceeds the noise power is found. Phase conjugation of a speckle field with a divergence of 2 × 10 -2 by a four-wave interaction with feedback was achieved experimentally for neodymium-activated glass and the efficiency was 5%. The input energy threshold was 100 mJ and the maximum energy in the phase-conjugate wave was 10 mJ.

Quantum Electronics•Mar 31, 1994•7 citations

Conjugate wave selection in four-wave mixing with feedback in a long nonlinear medium

Alexander A. Betin, A. V. Kirsanov

One of the efficient methods of phase conjugation (PC) is the four-wave mixing with feedback (FWMF) (Fig. 1). To select the wave conjugate to the input radiation in a FWMF resonator, it has been suggested to use either an inhomogeneous phase plate or a long (larger than the length of the longitudinal inhomogeneity of the signal) nonlinear medium.1 The diffraction efficiency of a thick hologram and its noises for a plane reference wave are calculated in Ref. 2. This paper provides the calculation of the power of the conjugate and noise waves produced by the reflection from a long phase hologram (mirror) recorded by two speckled beams. The paper also deals with experimental realization of a PC FWMF speckled beam in a long medium.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)•Jan 1, 1994•0 citations

Reflection of speckle-inhomogeneous CO2laser radiation under four-wave interaction conditions with feedback

Alexander A. Betin, Konstantin V. Ergakov, O V Mitropol'skiĭ

An experimental demonstration is reported of the feasibility of phase conjugation via a four-wave interaction with feedback in the case of pulsed CO 2 laser radiation with a speckle-inhomogeneous structure. Reflection of a speckle-inhomogeneous signal with a clear phase-conjugated structure against the background of a noise component is reported. Ways of improving the quality of the phase conjugation are discussed.

Quantum Electronics•Jan 31, 1994•4 citations

Passive phase conjugate mirror based on self-induced oscillation in an optical ring cavity

Mark Cronin‐Golomb, Baruch Fischer, Jeffrey Owen White +1 more

A passive phase conjugate mirror based on four-wave mixing in an optical ring cavity is described. Unlike previously demonstrated passive phase conjugate mirrors it generates only one of its pumping beams by nonlinear optical interactions, the other being provided by feedback of the probe after transmission through the nonlinear medium. The results of a theory yielding phase conjugate reflectivity and oscillation thresholds are presented together with an experimental demonstration of phase conjugation in barium titanate and strontium barium niobate. The device is self-starting by four-wave mixing, and has an oscillation threshold lower than that of other previously demonstrated passive phase conjugate mirrors with similar ease of alignment. The operation of a device which generates nonconjugate oscillation beams is also reported.

Applied Physics Letters•Jun 1, 1983•111 citations

High-reflectivity four-wave mixing by gain saturation of nanosecond and microsecond radiation in Nd:YAG

Michael J. Damzen, R.P.M. Green, Graham J. Crofts

High-reflectivity four-wave mixing by gain saturation in a Nd:YAG laser amplifier is demonstrated. With a four-pass geometry, the phase-conjugate reflectivity of a Q-switched pulse (18-ns duration) is ∼2500, and for a long pulse (relaxation oscillation duration ∼100 μs) it is ∼30. Temporal and energy characteristics of the conjugate beam are presented. A phase-conjugate Nd:YAG TEM00 laser resonator is also produced in which the Nd:YAG rod is simultaneously the laser gain medium and the phase-conjugating device.

Optics Letters•Oct 1, 1992•30 citations

Theory of phase conjugation by degenerate four-wave mixing using spatially varying pump beams

Erik J. Bochove

Phase-conjugate beam fidelity is studied in degenerate four-wave mixing with spatially varying pump beams. The theory includes long-cell-length (or high-gain) effects, diffraction, and nonlinear phase variation, focusing of the probe beam, and, finally, losses. Relatively simple algebraic expressions for the reflectivity are given that cover the cases of collinear or near-collinear beam geometries. An easily calculated parameter is defined that characterizes phase-conjugate fidelity and is applied to study focusing effects. It is shown that focusing effects may be useful in greatly reducing the principal distortion of the phase-conjugate beam over a considerable range of variation of beam parameters.

Journal of the Optical Society of America•Oct 1, 1983•17 citations
A study is reported of a system, making use of four-wave mixing with feedback (FWMF), for high-quality phase conjugation of speckle-inhomogeneous radiation. The system includes a hologram formed on the basis of nonlinearity of gain saturation. A theoretical analysis is made of selective capabilities of a 'short' hologram, whose length is less than the longitudinal correlation lengths of the 'write' waves used to form it. The statistical-average values of the parameters of modes in an FWMF cavity are determined. The experimental results obtained for a neodymium glass system show that the fidelity of phase conjugation of speckle beams with a divergence (5 — 25) θ diffr is 80%. The maximum energy of the phase-conjugated component is 0.35 J and the maximum energy reflection coefficient of an FWMF mirror is 20.
A quasi-optical approximation without allowance for beam spreading over its envelope is used to show that selection of a conjugate wave occurs in a volume hologram whose dimensions are greater than the longitudinal correlation length of the fields forming the hologram. The condition under which the signal power exceeds the noise power is found. Phase conjugation of a speckle field with a divergence of 2 × 10 -2 by a four-wave interaction with feedback was achieved experimentally for neodymium-activated glass and the efficiency was 5%. The input energy threshold was 100 mJ and the maximum energy in the phase-conjugate wave was 10 mJ.
One of the efficient methods of phase conjugation (PC) is the four-wave mixing with feedback (FWMF) (Fig. 1). To select the wave conjugate to the input radiation in a FWMF resonator, it has been suggested to use either an inhomogeneous phase plate or a long (larger than the length of the longitudinal inhomogeneity of the signal) nonlinear medium.1 The diffraction efficiency of a thick hologram and its noises for a plane reference wave are calculated in Ref. 2. This paper provides the calculation of the power of the conjugate and noise waves produced by the reflection from a long phase hologram (mirror) recorded by two speckled beams. The paper also deals with experimental realization of a PC FWMF speckled beam in a long medium.
A passive phase conjugate mirror based on four-wave mixing in an optical ring cavity is described. Unlike previously demonstrated passive phase conjugate mirrors it generates only one of its pumping beams by nonlinear optical interactions, the other being provided by feedback of the probe after transmission through the nonlinear medium. The results of a theory yielding phase conjugate reflectivity and oscillation thresholds are presented together with an experimental demonstration of phase conjugation in barium titanate and strontium barium niobate. The device is self-starting by four-wave mixing, and has an oscillation threshold lower than that of other previously demonstrated passive phase conjugate mirrors with similar ease of alignment. The operation of a device which generates nonconjugate oscillation beams is also reported.
High-reflectivity four-wave mixing by gain saturation in a Nd:YAG laser amplifier is demonstrated. With a four-pass geometry, the phase-conjugate reflectivity of a Q-switched pulse (18-ns duration) is ∼2500, and for a long pulse (relaxation oscillation duration ∼100 μs) it is ∼30. Temporal and energy characteristics of the conjugate beam are presented. A phase-conjugate Nd:YAG TEM00 laser resonator is also produced in which the Nd:YAG rod is simultaneously the laser gain medium and the phase-conjugating device.
Phase-conjugate beam fidelity is studied in degenerate four-wave mixing with spatially varying pump beams. The theory includes long-cell-length (or high-gain) effects, diffraction, and nonlinear phase variation, focusing of the probe beam, and, finally, losses. Relatively simple algebraic expressions for the reflectivity are given that cover the cases of collinear or near-collinear beam geometries. An easily calculated parameter is defined that characterizes phase-conjugate fidelity and is applied to study focusing effects. It is shown that focusing effects may be useful in greatly reducing the principal distortion of the phase-conjugate beam over a considerable range of variation of beam parameters.