Topical Meeting on Photorefractive Materials, Effects, and Devices II最新文献

{"title":"Direct measurements of charge carrier mobilities in photorefractive sillenite crystals","authors":"G. Pauliat, A. Villing, J. Launay, G. Roosen","doi":"10.1364/pmed.1990.a8","DOIUrl":"https://doi.org/10.1364/pmed.1990.a8","url":null,"abstract":"The charge carrier mobility*recombination time product (μτ) is an important photorefractive parameter. In the band transport model [1], this product is one of the three crystal parameters (with Na the deep trap density and τdi the dielectric recombination time) which govern the kinetics of the photorefractive effect. Usual photorefractive measurements of μτ are lengthy and give uncertain results for some samples in which the band transport model is not detained enough to completly describe the photorefractive effect.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"17 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":"132522025","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":"Photorefractive Effects in Ferromagnetic Semiconductors with Superlattice Formed by Coherent Light Beams","authors":"A. Semchuk","doi":"10.1364/pmed.1990.pd10","DOIUrl":"https://doi.org/10.1364/pmed.1990.pd10","url":null,"abstract":"Let us consider a wide-gap donor-type a ferromagnetic semiconductor (FMSC) with mean carrier density nOin the spin wave temperature range placed in an external constant electric field \u0000F→O//OZ, magnetic field \u0000H→O//F→O and variable weak magnetic field \u0000h→/H→O. Its face surface is subjected to several coherent light beams (CLBs), whose frequencies satisfe the inequality \u0000ε¯≪ℏω≪ε\u0000 g\u0000 (ε\u0000 g\u0000 is the energy-gap width). In this case, as a result of the interference phenomena, there appear new regularities in the character of the high-frequency CLB field influence on free carriers and magnons. Thus, for example, the spatial modulation of collision integrals and high-frequency light waves pressure force on electrons leads to the formation of superlattices of the carrier density, electron and magnon temperatures, electric field strength, and magnetization intensity in the system of non-equilibrium electrons and magnons of FMSC.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"16 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":"126473397","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":"Electron Irradiation Damage to KNbO3","authors":"E. Hodgson, C. Zaldo, F. Lopez","doi":"10.1364/pmed.1990.ap5","DOIUrl":"https://doi.org/10.1364/pmed.1990.ap5","url":null,"abstract":"The optical absorption induced by electron irradiation in KNbO3 has been investigated with a Van de Graaf accelerator. A well defined threshold energy of 0.35 MeV has been found to induce colouring. A broad band roughly peaked at 450 nm is formed above threshold. The observed coloration has been related to the displacement of oxygen atoms.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"52 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":"124599470","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":"Neutron diffraction — photorefractive materials enter a new research and application branch","authors":"R. Rupp, J. Hehmann, K. Ibel, R. Matull","doi":"10.1364/pmed.1990.pd3","DOIUrl":"https://doi.org/10.1364/pmed.1990.pd3","url":null,"abstract":"Light-induced changes of the refractive index are referred to as photorefractive effect. Thereby it does not matter whether the light causing and the light sensing these changes have different wavelengths—from the infrared to the 7-ray spectral region— or not. In this paper we intend to generalize the notion of a photorefractive effect to cover also light-induced changes of the refractive index for neutron waves (photorefractive effect of a second kind). The scope of possible applications of photorefractive materials is extended towards holographic optical elements for neutron optics.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"19 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":"115103009","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":"Planar Hologram Arrays in Photorefractive Waveguides in LiNbO3","authors":"I. Itkin, V. Shandarov, E. Shandarov, S. Shandarov","doi":"10.1364/pmed.1990.bp6","DOIUrl":"https://doi.org/10.1364/pmed.1990.bp6","url":null,"abstract":"The dynamics of hologram recording in optical waveguides on the basis of photorefractive crystals is determined by a number of factors, and among them there are types and indices of interacting modes [1-3], correlation between the periods of the array and thickness of the waveguide layer h, orientation of the substrate and array vector \u0000K→ relative to the crystallophysic axes [4]. The results of investigations of planar hologram array recording by the waveguide TE-modes in the structures on the basis of lithium niobate have been cited in the given report.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"12 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":"123473235","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":"Optical Image Processing : Spatial Filtering by Photorefractive Materials","authors":"H.W. Li, J. Gazengel, N. P. Xuan, J. Ferrier, J. Bourdin, G. Rivoire","doi":"10.1364/pmed.1990.jp5","DOIUrl":"https://doi.org/10.1364/pmed.1990.jp5","url":null,"abstract":"The nonlinearities of photorefractive materials such as Fe:LiNbO3, BSO, BGO,… are used to filter the Fourier spectrum of an object. Image processing techniques, such as contrast inversion or contrast enhancement of amplitude objects, and phase objects visualization are thus obtained with simple optical devices and low power cw lasers.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"313 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":"123326677","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":"Phase-Conjugate Fiber-Optic Gyros","authors":"I. Mcmichael, Bill Christian, P. Beckwith, M. Khoshnevisan, P. Yeh","doi":"10.1364/pmed.1990.j7","DOIUrl":"https://doi.org/10.1364/pmed.1990.j7","url":null,"abstract":"Phase-conjugate fiber-optic gyros (PCFOG’s) use phase conjugation to compensate for reciprocal phase changes due to thermal and mechanical effects on the fiber, while at the same time. allowing for the measurement of the nonreciprocal phase shift produced by rotation.1,2 Where the best standard fiber-optic gyros require polarization-preserving fibers and couplers to avoid polarization scrambling that is a source of noise and signal fading, the PCFOG can avoid this problem by using polarization-preserving phase conjugation.3 This has the advantage of allowing for the use of inexpensive nonpolarization preserving, and even multimode fibers and components.3-5 Our first objective was to demonstrate that the PCFOG is sensitive to the nonreciprocal phase shift produced by the Sagnac effect and can be used to sense rotation. A proof of concept experiment was set up for this objective using an externally-pumped crystal of barium titanate as the phase conjugator. This experiment, reported in Ref. 6, provided the first demonstration of rotation sensing with a PCFOG. In this proof of concept demonstration the length of the fiber-optic coil, and therefore the sensitivity of the gyro, was limited by the coherence length of the laser. To solve this problem we set up a PCFOG consisting of a Michelson interferometer in which the light beams from two arms travel as clockwise and counterclokwise beams respectively, in the same fiber optic coil and reflect from the same self-pumped phase-conjugator. We reported the demonstration of rotation sensing with this PCFOG in Ref. 7. Again, since phase conjugation can correct for modal scrambling, a PCFOG can use multimode fibers. However, complete correction of modal scrambling requires a polarization-preserving conjugator,5 and the corresponding experimental setup of a PCFOG is complicated. To solve this problem we set up a PCFOG using a multimode fiber coil, a nonpolarization-preserving conjugator,4 and a spatial filter to discriminate against the portion of the light reflected by the conjugator that does not correct for modal scrambling. This experiment, reported in Ref. 8, provided the first demonstration of rotation sensing with a PCFOG using multimode fiber.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"2015 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":"127693746","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":"Experimental Studies of Self-Pumped Photorefractive Ring Resonators","authors":"P. Hříbek, N.C. Gower","doi":"10.1364/pmed.1990.pd6","DOIUrl":"https://doi.org/10.1364/pmed.1990.pd6","url":null,"abstract":"In the setup shown in Fig.1, two-beam coupling with unidirectional oscillation in a ring resonator which contains a photorefractive BaTiO3 crystal was used to create a new type of self-pumped phase conjugate mirror.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"9 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":"127953642","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":"Optic and spectroscopic investigation in photorefractive BaTiO3 crystals","authors":"A. Maillard, P. Jullien","doi":"10.1364/pmed.1990.ap8","DOIUrl":"https://doi.org/10.1364/pmed.1990.ap8","url":null,"abstract":"To characterize BaTiO3 by optical measurements it is necessary to know spectroscopic results from the same sample. We propose datas from EPR, Mass spectroscopy, absorption and conclude about the diversity of samples.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"48 8 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":"125732417","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":"Investigations on Hologram Fixing Process in Sillenite Type Photorefractive Crystals","authors":"M. Miteva","doi":"10.1364/pmed.1990.g4","DOIUrl":"https://doi.org/10.1364/pmed.1990.g4","url":null,"abstract":"The holograms fixing process in very well known sillenite type photorefractive crystals Bi12(Ge, Si, Ti)O20 has important implications for various applications. An effect of prolonged memory of holographic recording with no applied electric field in photorefractive Bi12TiO20 (BTO) crystals at room temperature has been reported.1,2 The effect is established for high frequency holographic grating with K = 2π/Λ ~ 3×105 cm-1, where Λ is the grating period.","PeriodicalId":385625,"journal":{"name":"Topical Meeting on Photorefractive Materials, Effects, and Devices II","volume":"57 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":"133253098","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}