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

Incoherent-to-coherent conversion using a photorefractive self-pumped phase conjugator

Edward J. Sharp, Gregory J. Salamo, Ratnakar R. Neurgaonkar, Gary L. Wood, William W. Clark

Published Feb 1, 1992• 21 citations
Publisher

Abstract

The principle of incoherent-to-coherent conversion is demonstrated in several photorefractive oxide crystals using a self-pumped phase-conjugator geometry. Resolution in excess of 30 line pairs/mm has been obtained for writing beams of a few milliwatts of power. The combined read/write function for a single frame showed a time response of approximately 140 ms at an intensity of 1 W/cm2 for the crystals used in these demonstrations.

DOI
10.1364/ol.17.000207

Related papers

Response of a self-pumped phase-conjugate mirror for two mutually coherent inputs

Tokuyuki Honda, Hirokazu Matsumoto

Photorefractive self-pumped phase conjugation is attractive for its simplicity and high reflectivity with low-power light sources. In order to realize its potential applications, it is important to study its response. So far the response of a phase-conjugate wave has been described with its rise time. It has not studied how the phase-conjugate wave responds when the spatial structure of an input probe wave is changed dynamically. We investigated the response of the phase conjugate wave by using two mutually coherent input beams, which can be regarded as components of a probe wave, and by introducing sinusoidal phase changes into one of them with varied frequencies. Each input beam has a power of 6 mW at the wavelength of 515 nm. A BaTiO3 crystal was employed as a self-pumped phase-conjugate mirror.1 By measuring relative phase between the two output beams, which can be regarded as components of a phase-conjugate wave, we found the response characteristic represented by a time-lag of first order, which is similar to RC circuit. The response time thus determined was 0.32 s, which was much shorter than the rise time of 30 s obtained with the same condition.

Annual Meeting Optical Society of America•Jan 1, 1990•0 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

Optical Bistability in a Photorefractive Self-Pumped Phase-Conjugator

Jiasen Zhang, Shin Yoshikado, Tadashi Aruga

We demonstrate the bistable behavior in a photorefractive self-pumped phase-conjugator (SPPC) theoretically and experimentally. In the method, an incoherent erase beam is used to erase the four-wave mixing (FWM) region of the SPPC, and thus the threshold of the SPPC depends on the intensity ratio of the erase beam to the sum of the coherent beams in the FWM region. Even a white light can be used to control the reflectivity as a switch.

Japanese Journal of Applied Physics•Jan 15, 2002•0 citations

Amplification of amplitude modulated signals in a self-pumped photorefractive phase conjugator

Paul Michael Petersen, Preben Buchhave

The properties of a self-pumped photorefractive phase conjugator as an amplifier of amplitude modulated signal beams are investigated. In principle the crystal acts as a self-adjusting beam combiner which allows homodyne detection of the weaksignalbeam superimposed on a stronger reference beam. In our experiments the mixing takes placevia a four wave interaction process in the crystal. In this paperwe investigate the salient characteristics ofthe self-pumped phase conjugate amplifier and explain details of the beam interaction inside the ciystal.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Feb 1, 1991•0 citations

Optical phase conjugation with a sodium Raman laser

Joanne DiFrancisco‐Donoghue, Jonathan S. Kane, Philip Hemmer

Recently, there has been increased interest in the use of resonant atomic systems for performing optical-wavefront conjugation. This interest has arisen because resonant systems are inherently fast, with response times in the nanosecond range. However, resonant systems tend to have lower efficiencies and greater optical power requirements than do photorefractive crystals, such as BaTiO3. In this paper, we explore the possibility of using a highly efficient Raman laser1 in a sodium-vapor cell to obtain efficient phase conjugation at greatly reduced optical power densities. In this demonstration we use a self-pumped (linear-cavity) conjugator for simplicity. With this setup, we have achieved phase- conjugate reflectivities of 2% with input powers of only 20 W/cm2. This is only 2% of the optical power density previously reported2 to obtain comparable reflectivity with a self-pumped scheme in sodium vapor.

Quantum Electronics and Laser Science Conference•May 12, 1991•0 citations

Photorefractive phase conjugators

M. D. Ewbank

The demonstration of optical phase conjugation in photorefractive materials has been accomplished by numerous methods, including i) externally-pumped four-wave mixing,1ii) self-pumped (passive) phase conjugation,24iii) stimulated backscattering,5,6and iv) mutually-pumped phase conjugation.7-10Stimulated backscattering and self-pumped phase conjugators have only a single incident beam. On the other hand, externally-pumped four-wave mixing has two auxiliary pumping beams in addition to the incident probe beam. Different still is the cross-conjugation of the two incident beams in mutually pumped phase conjugators. To use these conjugators in a given application, the compatibility between the processes generating the phase-conjugate wave(s) and the application must be considered. The distinguishing features of the different conjugators translate to advantages or disadvantages for certain applications.

Digest on Nonlinear Optics: Materials, Phenomena and Devices•Jan 1, 1990•1 citation
The principle of incoherent-to-coherent conversion is demonstrated in several photorefractive oxide crystals using a self-pumped phase-conjugator geometry. Resolution in excess of 30 line pairs/mm has been obtained for writing beams of a few milliwatts of power. The combined read/write function for a single frame showed a time response of approximately 140 ms at an intensity of 1 W/cm2 for the crystals used in these demonstrations.
Photorefractive self-pumped phase conjugation is attractive for its simplicity and high reflectivity with low-power light sources. In order to realize its potential applications, it is important to study its response. So far the response of a phase-conjugate wave has been described with its rise time. It has not studied how the phase-conjugate wave responds when the spatial structure of an input probe wave is changed dynamically. We investigated the response of the phase conjugate wave by using two mutually coherent input beams, which can be regarded as components of a probe wave, and by introducing sinusoidal phase changes into one of them with varied frequencies. Each input beam has a power of 6 mW at the wavelength of 515 nm. A BaTiO3 crystal was employed as a self-pumped phase-conjugate mirror.1 By measuring relative phase between the two output beams, which can be regarded as components of a phase-conjugate wave, we found the response characteristic represented by a time-lag of first order, which is similar to RC circuit. The response time thus determined was 0.32 s, which was much shorter than the rise time of 30 s obtained with the same condition.
The properties of a self-pumped photorefractive phase conjugator as an amplifier of amplitude modulated signal beams are investigated. In principle the crystal acts as a self-adjusting beam combiner which allows homodyne detection of the weaksignalbeam superimposed on a stronger reference beam. In our experiments the mixing takes placevia a four wave interaction process in the crystal. In this paperwe investigate the salient characteristics ofthe self-pumped phase conjugate amplifier and explain details of the beam interaction inside the ciystal.
Recently, there has been increased interest in the use of resonant atomic systems for performing optical-wavefront conjugation. This interest has arisen because resonant systems are inherently fast, with response times in the nanosecond range. However, resonant systems tend to have lower efficiencies and greater optical power requirements than do photorefractive crystals, such as BaTiO3. In this paper, we explore the possibility of using a highly efficient Raman laser1 in a sodium-vapor cell to obtain efficient phase conjugation at greatly reduced optical power densities. In this demonstration we use a self-pumped (linear-cavity) conjugator for simplicity. With this setup, we have achieved phase- conjugate reflectivities of 2% with input powers of only 20 W/cm2. This is only 2% of the optical power density previously reported2 to obtain comparable reflectivity with a self-pumped scheme in sodium vapor.
The demonstration of optical phase conjugation in photorefractive materials has been accomplished by numerous methods, including i) externally-pumped four-wave mixing,1ii) self-pumped (passive) phase conjugation,24iii) stimulated backscattering,5,6and iv) mutually-pumped phase conjugation.7-10Stimulated backscattering and self-pumped phase conjugators have only a single incident beam. On the other hand, externally-pumped four-wave mixing has two auxiliary pumping beams in addition to the incident probe beam. Different still is the cross-conjugation of the two incident beams in mutually pumped phase conjugators. To use these conjugators in a given application, the compatibility between the processes generating the phase-conjugate wave(s) and the application must be considered. The distinguishing features of the different conjugators translate to advantages or disadvantages for certain applications.