{"title":"Route to chaotic structures in a phase-conjugate ring-resonator during self-oscillation","authors":"R. Blumrich, T. Kobialka, T. Tschudi","doi":"10.1364/pmed.1990.e3","DOIUrl":"https://doi.org/10.1364/pmed.1990.e3","url":null,"abstract":"The sytem we investigated is called phase-conjugate ring-resonator (PCR). It consists of a Sagnac interferometer and a phase-conjugate mirror (PCM) realized by four-wave mixing in a photorefractive BaTiO3-crystal. Since the PCM provides nonlinear gain and high amplification, the PCR forms a nonlinear, active feedback system with a large image plane and a high resolution [1].","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133405115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Venkateswarlu, M. Moghbel, P. C. Sekhar, M. George
{"title":"Effects of Phase Conjugation and of Coherent and Incoherent Beam Couplings in Reflection and Transmission in BaTiO3","authors":"P. Venkateswarlu, M. Moghbel, P. C. Sekhar, M. George","doi":"10.1364/pmed.1990.ip2","DOIUrl":"https://doi.org/10.1364/pmed.1990.ip2","url":null,"abstract":"We reported recently1 coherent beam couplings with He-Ne laser in reflection and transmission in electrically poled BaTiO3. We report here effects of phase conjugation on reflection and transmission. The effects of coherent and incoherent beam couplings on reflection and transmission will be compared. The experimental configuration used in the present experiments is shown in Fig. 1a. Two mutually coherent beams A1 and A2 from a He-Ne laser (6328Å) cross in the BaTiO3 crystal at 5°, with A1 and A2 making 73° and 78° with the c axis respectively. A third beam A3 from a second laser (6328Å) makes a crossing angle of 11° with A1 in the crystal. The self-pumped phase conjugate \u0000A←1(t) of the beam A1, its transmitted part A1T1 after one reflection and the specular reflection A1R1 are examined along with the subsequent transmission and reflection beams A1T2 and A1R2 respectively. The development of these five different beams is shown in Fig. 1b. Fig. 2 shows the specular reflection A1R1, being steady for a while, begins to go down as the self-pumped phase conjugate \u0000A←1(t) and the transmission beam A1T1 develop, and saturates at a lower intensity level.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133424149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Two-photon Absorption and Transient Energy Transfer in BaTiO3","authors":"J. O. White, T. Boggess, G. Valley","doi":"10.1364/pmed.1990.d1","DOIUrl":"https://doi.org/10.1364/pmed.1990.d1","url":null,"abstract":"We have used ultrashort optical pulses to investigate bound electronic, free carrier, and photorefractive nonlinearities, as well as induced absorption in BaTiO3. A pump-probe technique was used to measure both an instantaneous two-photon absorption and a long-lived induced absorption. Measurements were taken with co-polarized and cross-polarized pump and probe pulses to identify any transient energy transfer associated with free-carrier gratings.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124959486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Nonlinear Neurons Using the Fieldshielding Effect in Photorefractive CdTe","authors":"M. Ziari, W. Steier, R. Devine","doi":"10.1364/pmed.1990.h3","DOIUrl":"https://doi.org/10.1364/pmed.1990.h3","url":null,"abstract":"A key element in the optical implementation of any neural network is the nonlinear neuron. The most common required feature of this device is a saturating response to an activation input. The activation input is the weighted sum of all the incident beams which are routed through an interconnection network to the neuron. We report on nonlinear neurons using the fieldshielding effect in photorefractive crystals which perform an incoherent addition of the incident intensities1,2. The device responds to CW or synchronously pulsed inputs in a variety of saturated, thresholded or bidirectional manners. Using photorefractive CdTe:In, we demonstrate a response to both inhibitory and excitatory inputs with a high sensitivity to incident light in the 1.0-1.4 μm range.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130195891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Examination of Electric Fields in Ferroelectrics by Impact Ionization","authors":"T. A. Rost, T. Rabson","doi":"10.1364/pmed.1990.bp4","DOIUrl":"https://doi.org/10.1364/pmed.1990.bp4","url":null,"abstract":"The space charge fields present in ferroelectric thin films are examined with impact ionization. The possibility of using this technique as a probe to aid in the understanding of the bulk photovoltaic effect is discussed.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129575246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Holographic Recording and Beam Coupling in Photorepractiv Media with Photo-Induced Light Scattering","authors":"A. Knyazkov, M. N. Lobanov","doi":"10.1364/pmed.1990.i1","DOIUrl":"https://doi.org/10.1364/pmed.1990.i1","url":null,"abstract":"Hologram recording and beam coupling in photorefractive media are accompanied by photo-indueed light scattering (PILS). The origin of this phenomenon lies in the recording of numerous noisy dynamic phase gratings formed by the original incident waves and by waves scattered from optical inhomogeneities [1]. Each scattered wave forms, with the incedent waves, a stationary interference pattern that produces the so-called noise hologram. These gratings can be spatially shifted that cause the amplification of scattered waves. In consequence the intensity of initial beams are changed essentially and hologram formation may be disturbed considerably also.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121465146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An Analytic Expression for the Photorefractive Two Beam Coupling Response Time","authors":"F. Vachss","doi":"10.1364/pmed.1990.bp8","DOIUrl":"https://doi.org/10.1364/pmed.1990.bp8","url":null,"abstract":"Among the most widely used properties of photorefractive materials is their ability to couple energy between two beams overlapping within the medium. This property allows for a weak information carrying beam to be amplified at the expense of a strong pump beam and thus provides a fundamental building block in a variety of applications of practical interest including optical interconnection and computing, image processing and laser hardening. In engineering such optical systems involving a photorefractive amplifier, accurately predicting the speed at which the amplifier will respond becomes a necessary facet of system design. As a result, the temporal response of the photorefractive effect has been the subject of extensive investigation. In the absence of two beam coupling, these investigations have resulted in explicit expressions for the photorefractive response time as a function of various relevant material and environmental parameters. While similar expressions valid when beam coupling is present have not yet been presented, and indeed are the subject of this paper, substantial progress toward their development has been made previously by other workers.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124541814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Size Effects in Volume Holograms Recorded in Photorefractive Crystals","authors":"F. Dubois, F. D. De Schryver, P. Lemaire","doi":"10.1364/pmed.1990.jp9","DOIUrl":"https://doi.org/10.1364/pmed.1990.jp9","url":null,"abstract":"In several applications as pattern recognition by dynamic coherent optical correlation, interference patterns whose typical width is of the same order of magnitude or less than the thickness of the recording materials are recorded in the bulk of photorefractive materials. In addition to the well known Bragg selectivity of the volume holograms, this geometric configuration influences the diffraction behavior of the reading beam. We have theoretically investigated this effect and experimental results are provided.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122639736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Investigation of phase shift of holographic gratings in photorefractive materials","authors":"M. Zha, P. Amrhein, P. Günter","doi":"10.1364/pmed.1990.i2","DOIUrl":"https://doi.org/10.1364/pmed.1990.i2","url":null,"abstract":"The fundamental processes occurring during the writing of phase gratings in photorefractive materials have been studied extensively in the past 1,2. Due to different mechanisms of carrier transportation these holograms may be phase shifted with respect to the interference pattern. This phase shift is of fundamental significance for the understanding of the mechanism of the photorefractive effect and for applications. We present a novel method for measuring the phase shift and some experimental results.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115440344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Sochava, S. Stepanov, S. Odoulov, S. Slussarenko, K. Shcherbin
{"title":"Photorefractive Beam-Coupling in BSO Crystals in Near Infrared","authors":"S. Sochava, S. Stepanov, S. Odoulov, S. Slussarenko, K. Shcherbin","doi":"10.1364/pmed.1990.ip1","DOIUrl":"https://doi.org/10.1364/pmed.1990.ip1","url":null,"abstract":"Dynamic holographic recording in sillenite type photorefractive crystals Bi12SiO20 (BSO)1 is very carefully investigated in visible region of spectrum. Two promising techniques (recording by the moving or oscillating light fringes in DC electric field or recording by stable fringes in AC electric field) were proposed to improve the beam coupling efficiency in these materials; the gain factor up to 6.12cm−1 is now obtained2,3. Present paper describes the first study of the dynamic coupling of two light beams in BSO crystals in near infrared. The measured values of the gain factor indicate the possibility of the development of coherent oscillators pumped by semiconductor lasers (including passive phase conjugating mirrors).","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115805208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}