{"title":"Picosecond Photorefractive and Free-Carrier Nonlinearities in Semiconductors","authors":"A. Smirl, J. Dubard, G. Valley, T. Boggess","doi":"10.1364/nlopm.1988.mc3","DOIUrl":"https://doi.org/10.1364/nlopm.1988.mc3","url":null,"abstract":"A variety of picosecond time-resolved two-beam coupling, transient grating and degenerate-four-wave mixing techniques are used to investigate the nonlinear loss and to measure the strength, formation and decay of photorefractive gratings written in GaAs and InP:Fe and of free-carrier gratings written in Si, GaAs, and InP by 43-ps pulses at a wavelength of 1 μm. We present data and numerical calculations as a function of fluence, time delay, pump-to-probe ratio, pump polarization, analyzer angle and crystal orientation. We observe photorefractive gains of a few percent at fluences of a few pJ/μm2 (0.1 mJ/cm2) in GaAs and InP, and we identify two sources for the photorefractive space-charge field. It is principally between mobile free carriers and stationary single-photon ionized donors at low fluences and between mobile electrons and holes produced by two-photon absorption at high fluences. We also observe strong transient energy transfer from the nominally \"unshifted\" free-carrier index gratings written in GaAs and InP by two-photon absorption and in Si by single-photon indirect absorption. We have demonstrated optical switches based on the pump-induced photorefractive rotation of the probe polarization in GaAs with on/off ratios of >2/1 at fluences as low as 400 fJ/μm2 and optical switches based on free-carrier transient-energy-transfer with on/off ratios >20,000/1 at 200 pJ/μm2. We have also used transient-energy-transfer to construct weak beam amplifiers with gains >25 at 30 mJ/cm2. Finally, these techniques have been used to obtain information about the properties of the deep-level (mid-gap) states in GaAs (EL2/EL2+) and InP (Fe2+/Fe3+), such as the cross sections and number densities.","PeriodicalId":208307,"journal":{"name":"Nonlinear Optical Properties of Materials","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":"117342783","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-Wave Mixing in Saturable Absorbers and Ranging Applications","authors":"S. Boothroyd, J. Chrostowski, M. O’Sullivan","doi":"10.1364/nlopm.1988.mf4","DOIUrl":"https://doi.org/10.1364/nlopm.1988.mf4","url":null,"abstract":"When two coherent light beams overlap in a saturable absorber, the materials refractive index is altered in phase with the light intensity distribution and a volume phase and/or absorption grating is created. A frequency shift introduced on one of the beams causes the fringe pattern to move. In materials with a finite response time, τ, a phase lag between the grating and the intensity pattern is produced and exchange of energy between the beams can occur.","PeriodicalId":208307,"journal":{"name":"Nonlinear Optical Properties of Materials","volume":"132 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120981781","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":"Potassium Titanyl Phosphate (KTP) Properties and New Applications","authors":"J. Bierlein","doi":"10.1364/nlopm.1988.wc2","DOIUrl":"https://doi.org/10.1364/nlopm.1988.wc2","url":null,"abstract":"KTP is a superior material for various nonlinear optical applications including second harmonic generation of the Nd:YAG 1.06 micron laser1. It is not hydroscopic, has large nonlinear optic coefficients and high damage thresholds, has small beam walkoff, and has large thermal and angular bandwidths. In addition KTP has large electrooptic coefficients and low dielectric constants which make it potentially useful for electrooptic applications.2 It has the largest optical waveguide modulator figure-of-merit of any known inorganic material.","PeriodicalId":208307,"journal":{"name":"Nonlinear Optical Properties of Materials","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":"126743632","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}
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