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

Optics Letters

Low-noise amplification of ultraweak optical wave fronts in photorefractive Bi_12SiO_20

Henri J. Rajbenbach, A. Delboulbé, Jean‐Pierre Huignard

Published Oct 1, 1991• 20 citations
Publisher

Abstract

We propose and demonstrate a technique for suppressing the optical noise of the photorefractive amplifiers that exhibit a sharp gain resonance around an optimum pump-to-signal angle. The amplification of extremely weak images is achieved when the entrance face of the crystal is tilted with respect to the pump beam direction. In Bi(12)SiO(20) subpicowatt optical signals are detected with this technique.

DOI
10.1364/ol.16.001481

Related papers

Noise reduction in photorefractive image amplifiers and applications

J.-P. Huignard, Henri J. Rajbenbach

We propose and experimentally demonstrate two original methods for suppressing the beam fanning noise of photorefractive amplifiers. The first one involves two wave mixing in a slowly rotating crystal, while the second requires to tilt the crystal with respect to the recording beams. This method applies to materials which exhibit a sharp resonance of the gain versus the pump-probe beam angle. With both methods a large improvement of the S/N ratio is achieved and virtually noise free image amplifiers are demonstrated. In Bi12SiO20, subpicowatt optical signals are detected and amplified. By using combinations of LiNbO3/Bi12SiO20, as storage and amplification crystals respectively a long term readout (more than 20 hours) of a photorefractive memory is achieved.

Journal de Physique III•Jul 1, 1993•0 citations

Noise-free Photorefractive Image Amplifiers

Henri J. Rajbenbach, A. Delboulbé, Jean‐Pierre Huignard

When a weak optical signal is injected in a photorefractive crystal illuminated with a strong pump beam, it experiences gain via a two-wave mixing process.(1) A problem common to these amplifiers is the presence of noise sources that corrupt the quality of the emerging amplified optical signal. We propose and experimentally demonstrate the first technique, to our knowledge, capable of very significantly reducing the optical noise while maintaining high gain coefficients. Consider two-wave mixing in a slowly rotating crystal. First, we estimate the influence of a crystal rotation (angular velocity Ω around the point O) on the noise intensity in the output plane (Fig. 1a). A noise source located around point A radiates a complex wavefront whose component along the direction of the injected signal is represented by a plane wave of intensity IN (A is a crystal imperfection or interface). It is essential to note that the noise sources are bounded to the crystal and will consequently move with it. This is the basis for the process of discrimination between the noise gratings and the injected signal grating. In the Ox coordinate bounded to the rotating crystal, the interference pattern responsible for the formation of a noise grating around the point A is given by: IN(x,t) = I0 [1 + mN cos KN(t)x], where KN(t) ~ 2π(θ + Ωt)/λ is the time-dependent grating wave vector (we have assumed that the angles inside the crystal are small), I0 is the total incident intensity (I0 ~ IP0), θ is the angle between the beams inside the crystal, λ = λ0/n is the optical wavelength in the crystal with refractive index n, and mN is the fringe modulation.

Photorefractive Effects, Materials, and Devices•Jan 1, 1990•0 citations

Photorefractive fourier image amplification for low-light-level image detection

G. C. Gilbreath, John F. Reintjes

In this article we demonstrate viable photorefractive image amplification in BaTiO3 at extremely low light levels. Uniform image amplification was observed over a range of intensity levels for different beam ratios. The technique is shown to be robust against beam fanning, the primary source of noise in multibeam photorefractive interactions in ferroelectric crystals. © 1996 John Wiley & Sons, Inc.

Microwave and Optical Technology Letters•Jun 20, 1996•3 citations

Noise in χ^(3) and photorefractive amplifiers

Shmuel Sternklar, Yaakov Glick

A comparison of the noise characteristics of χ(3) and photorefractive coherent amplifiers reveals basic differences in their dependence on operating parameters. Unlike all types of χ(3) amplifiers, which are shown to have a well-defined optimum working point in the region of the self-stimulated scattering threshold, the photorefractive amplifier can be made increasingly quieter by lowering the pump power. This is demonstrated by use of highly doped Co:BaTiO3 in a tight-focus reflection grating geometry. It is shown that scattering from inhomogeneities in the crystal is the major limiting noise source and is significantly higher than predictions resulting from fundamental considerations such as random space-charge noise. An extremely high small-signal gain of 107 was measured with this crystal and geometry. To our knowledge this is the highest photorefractive gain reported to date.

Optics Letters•Dec 1, 1995•5 citations

Self-induced coherent oscillations with photorefractive Bi_12SiO_20 amplifier

Henri J. Rajbenbach, Jean‐Pierre Huignard

We report coherent oscillations due to self-induced moving gratings in photorefractive BSO crystals when recording with an external applied field. Different types of ring and phase-conjugate resonators pumped with low-incident- intensity beams and having short response times are demonstrated. The conditions permitting oscillation and the respective frequencies of the pump and the signal beams in the cavity are analyzed.

Optics Letters•Mar 1, 1985•123 citations

Pulsed amplification of continuous-wave signal fields in photorefractive BaTiO3

Nikolaos A. Vainos, S. Mailis, M. C. Gower

High-gain pulsed amplification of low intensity continuous-wave optical signals via two-wave mixing in a photorefractive barium titanate (BaTiO3) crystal is demonstrated. The technique relies on the nonlinear mixing between a signal field and a pump field produced via pulsed amplification of a continuous-wave field in excimer-pumped dye amplifiers.

Applied Physics Letters•Mar 30, 1992•2 citations
We propose and demonstrate a technique for suppressing the optical noise of the photorefractive amplifiers that exhibit a sharp gain resonance around an optimum pump-to-signal angle. The amplification of extremely weak images is achieved when the entrance face of the crystal is tilted with respect to the pump beam direction. In Bi(12)SiO(20) subpicowatt optical signals are detected with this technique.
We propose and experimentally demonstrate two original methods for suppressing the beam fanning noise of photorefractive amplifiers. The first one involves two wave mixing in a slowly rotating crystal, while the second requires to tilt the crystal with respect to the recording beams. This method applies to materials which exhibit a sharp resonance of the gain versus the pump-probe beam angle. With both methods a large improvement of the S/N ratio is achieved and virtually noise free image amplifiers are demonstrated. In Bi12SiO20, subpicowatt optical signals are detected and amplified. By using combinations of LiNbO3/Bi12SiO20, as storage and amplification crystals respectively a long term readout (more than 20 hours) of a photorefractive memory is achieved.
When a weak optical signal is injected in a photorefractive crystal illuminated with a strong pump beam, it experiences gain via a two-wave mixing process.(1) A problem common to these amplifiers is the presence of noise sources that corrupt the quality of the emerging amplified optical signal. We propose and experimentally demonstrate the first technique, to our knowledge, capable of very significantly reducing the optical noise while maintaining high gain coefficients. Consider two-wave mixing in a slowly rotating crystal. First, we estimate the influence of a crystal rotation (angular velocity Ω around the point O) on the noise intensity in the output plane (Fig. 1a). A noise source located around point A radiates a complex wavefront whose component along the direction of the injected signal is represented by a plane wave of intensity IN (A is a crystal imperfection or interface). It is essential to note that the noise sources are bounded to the crystal and will consequently move with it. This is the basis for the process of discrimination between the noise gratings and the injected signal grating. In the Ox coordinate bounded to the rotating crystal, the interference pattern responsible for the formation of a noise grating around the point A is given by: IN(x,t) = I0 [1 + mN cos KN(t)x], where KN(t) ~ 2π(θ + Ωt)/λ is the time-dependent grating wave vector (we have assumed that the angles inside the crystal are small), I0 is the total incident intensity (I0 ~ IP0), θ is the angle between the beams inside the crystal, λ = λ0/n is the optical wavelength in the crystal with refractive index n, and mN is the fringe modulation.
A comparison of the noise characteristics of χ(3) and photorefractive coherent amplifiers reveals basic differences in their dependence on operating parameters. Unlike all types of χ(3) amplifiers, which are shown to have a well-defined optimum working point in the region of the self-stimulated scattering threshold, the photorefractive amplifier can be made increasingly quieter by lowering the pump power. This is demonstrated by use of highly doped Co:BaTiO3 in a tight-focus reflection grating geometry. It is shown that scattering from inhomogeneities in the crystal is the major limiting noise source and is significantly higher than predictions resulting from fundamental considerations such as random space-charge noise. An extremely high small-signal gain of 107 was measured with this crystal and geometry. To our knowledge this is the highest photorefractive gain reported to date.