{"title":"Photoconducting antennas","authors":"D. Auston, M. Nuss, P. Smith","doi":"10.1364/ils.1986.tuk1","DOIUrl":"https://doi.org/10.1364/ils.1986.tuk1","url":null,"abstract":"Photoconductors have proved to be extremely effective sources of very short electrical pulses.1 When illuminated by ultrafast optical pulses they have been used to generate electrical transients as fast as 0.5 ps. The frequency spectrum of these pulses extends from dc up to terahertz frequencies, making them potentially useful sources of microwave, millimeter-wave and far-infrared radiation.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"332 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":"122742907","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":"Laser diagnostics beyond two dimensions","authors":"M. Long, B. Yip","doi":"10.1364/ils.1986.fc2","DOIUrl":"https://doi.org/10.1364/ils.1986.fc2","url":null,"abstract":"Laser-diagnostic imaging techniques have become a useful tool for measurement of quantities such as species concentration and temperature in reacting and nonreacting turbulent flows. These techniques are valuable for determining the spatial character of large-scale structures in these flows because of their capability for simultaneous measurement at a large number of points in a plane intersecting the flow. A basic characteristic of turbulence, however, is its 3-D nature and thus fully 3-D data would be desirable. A new experimental technique has been developed which can produce an instantaneous 3-D mapping of the gas concentration in an aerosol-seeded flow. Three-dimensional measurements are obtained by measuring the 2-D gas concentration distribution in many closely spaced parallel sheets. These measurements must all be completed in a short time to effectively freeze the flow. This is accomplished by sweeping a thin sheet of rapidly pulsed laser illumination (30-kHz pulses from a cavity-dumped argon-ion laser) through the flow and recording the scattered light intensity from different laser pulses on different regions of a computer-controlled detector. The resulting volume measurements can be visualized using computer graphics to display surfaces of constant material properties.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"65 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":"122897818","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":"Study of triplet states by equal-frequency two-photon transitions in Na2","authors":"H. Xia, Jian-Wen Xu, Zuo-Di Pan, Ji-Guang Cai, Long-Shen Ma, Lina Cheng","doi":"10.1364/ils.1986.thl21","DOIUrl":"https://doi.org/10.1364/ils.1986.thl21","url":null,"abstract":"The experiments were arranged with a pulsed dye laser and a cross oven. A double-pen chart recorder simultaneously traced the two-photon excitation spectra monitored by two photomultipliers with interference filters centered at 3600 and 4300 Å, respectively. The observed two-photon transitions with a linewidth of ~0.2 Å were distributed discretely and nonuniformly and were close to the calculated values for searching the intermediate singlet-triplet mixing levels in Na2. This means that the observed signals were individually enhanced by a near-resonant mixing level. While most of the corresponding recorded lines in the two traces had coincident wavelength locations and comparable intensities, a part of the lines at the longer wavelength sides of the traces with moderate or weaker intensities appeared alternately. The upper states for the lines which only appeared in the 4300 Å trace or in both of the traces were assumed to be (2)3Π\u0000 g\u0000 and a higher (n)3Λ\u0000 g\u0000 state, respectively. Temperature and total pressure was varied. Finally, the laser beam was split into two with combined polarization situations. These aided the identification of the two- photon transitions.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"59 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":"114176486","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":"Fluctuation-induced resonances","authors":"Y. Prior, P. Stern","doi":"10.1364/ils.1986.we1","DOIUrl":"https://doi.org/10.1364/ils.1986.we1","url":null,"abstract":"Recently1 a detailed analysis was given for the role played by laser phase fluctuations in NL optics. In that work, the existence of new extra resonances induced by stochastic fluctuations was predicted, based on a derivation starting from the phase diffusion model. In this work we present the results of numerical simulations of laser phase fluctuations. The optical Bloch equations are solved numerically for a phase fluctuating laser. A model of a piecewise constant phase jumping at random between all values is treated, and other models are discussed. Molecular collisions are simulated and compared to phase fluctuations. The collisions give rise to the pressure-induced extra resonance (PIER4), while the phase jumps give rise to stochastic fluctuations-induced extra resonance (SFIER). These simulations show clearly that phase fluctuations may be analogous to real collisions and may cause extra resonances, and indeed, the SFIER4 resonance has recently been observed experimentally.2","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"101 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":"130344441","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":"Effects of fluctuations on quantum and nonlinear optical processes","authors":"J. Eberly","doi":"10.1364/ils.1986.wb1","DOIUrl":"https://doi.org/10.1364/ils.1986.wb1","url":null,"abstract":"Examples from recent work with K. Wodkiewicz, M. Jamanol and J. J. Yeh will be used to review the kinds of effects that may be expected when stochastic fluctuations are imposed on quantum and nonlinear optical processes.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","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":"130638638","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":"Near-threshold ion photofragment spectroscopy","authors":"P. Sarre, J. M. Walmsley, C. J. Whitham","doi":"10.1364/ils.1986.tul2","DOIUrl":"https://doi.org/10.1364/ils.1986.tul2","url":null,"abstract":"We have recorded high-resolution laser photofragment spectra of the astrophysically important ions CH+ and SiH+. The experiments are designed to give information on the region of internuclear distance between the atomic and molecular limits for systems where dissociation occurs into atoms possessing electronic angular momentum, in this case C+(2P) or Si+(2P). A-keV beam of Ch+ (SiH+) is irradiated coaxially with cw single-mode tunable laser radiation which induces transitions from the X1∑+ ground state to predissociated levels of the A1∏ state and other electronic states which correlate with the C+(2P) + H(2S) or Si+(2S) limit. An electrostatic analyzer provides mass and energy selection of the photofragment C+ or Si+ ions which are detected with an electron multiplier. Information is obtained from transition frequencies, hyperfine splittings, predissociation linewidths, and also from the photofragment kinetic energies and angular distributions. Over thirty transitions to 1∏ levels have been detected in CH+ (Ref. 1); in SiH+ we have observed transitions to levels which almost certainly lie between the Si+(2P1/2,2P3/2) + H(2S) fine structure limits. We have also recorded numerous resonances in both ions which arise from transitions to triplet states which correlate to the same dissociation limit and are observable because of strong nonadiabatic couplings.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"22 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":"125969047","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":"Coherent pump dynamics, depletion, and transverse effects on the superfluorescence/Stokes/probe (SF, St, Prb) beam buildup and its asymptotic evolution of a stabilized on-axis swept-gain Raman forward amplifiers/spectroscopy studies","authors":"F. Mattar, P. Berman","doi":"10.1364/ils.1986.thc6","DOIUrl":"https://doi.org/10.1364/ils.1986.thc6","url":null,"abstract":"A computer movie illustrating a rigorous multimode calculation of SF, St, Prb buildup in Raman studies is presented. This coherent copropagational study based on Maxwell-Bloch formalism1 includes phase and transverse variations, nonlinear asymmetric dispersion, pump spatial depletion, and time-dependent variations in population inversion density. Theλ scheme is selected so that the active transitions are optically thick for both the pump (α\u0000 p\u0000 l > 5) and the SF (α\u0000 sf\u0000 l > 35) pulses. This choice of Beer lengths, i.e., of oscillator strengths, insures that the two pulses never cease to overlap and optimizes the SF initially small signal growth. The pump interacts like a self-induced transparency while the SF, St, Prb evolves as a small-area in a two-level emitter which can be described as a nonlinear pendulum in the pane wave. For a given ratio of Beer lengths, distinct Fresnel numbers, atomic density numbers, small signal SF, St, Prb time-integrated energy stabilization or self-focusing may arise, as observed experimentally. For a sufficiently larger propagation distance, an asymptotic evolution of a quasisolitary nonhyperbolic-secant pulse of constant area is reported.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"3 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":"134390016","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":"Properties of an optical cavity for a high-power CO2 laser","authors":"G. Rabczuk","doi":"10.1364/ils.1986.thl6","DOIUrl":"https://doi.org/10.1364/ils.1986.thl6","url":null,"abstract":"Properties of a positive-branch nonconfocal unstable resonator in a one- and two-pass (folded) configuration, designed for a CO2-N2-He transverse flow laser excited by a high-power glow discharge1 have been studied numerically. Calculations were carried out with the help of a computer code2 that takes into account an idealized, saturable, homogeneously broadened gain medium model. The near- and far-field behavior of both configurations, as well as the theoretical dependence of the output power (P) on the small signal-gain (g0), saturation intensity (Is), mirror reflectivity (R\u0000 i\u0000 ), and the discharge length (L\u0000 a\u0000 ) are discussed. For g0 = 0.4/m (the average value of g0 found experimentally), l\u0000 s\u0000 = 0.5 kW/cm2, R\u0000 j\u0000 , = 0.88, and L\u0000 a\u0000 = 0.86m, our calculations predict for the one-pass cavity P = 1.6 kW and for the two-pass cavity P = 4.2 kW; measured values of P were ~1.7 and ~4.4 kW, respectively. The calculations also predict the rather poor quality of the output beam. In both cases ~90% of the output power is focused within a circle of angular width 2θ = 1.06 mrad, but only a small fraction of the beam energy (~40%) is contained in the centermost beam lobe (2θ = 0.3 mrad). According to the mirror tilt analysis there is no significant difference in the tolerances of both cavities to angular misalignment. With increasing mirror tilt noticeable distortions in the far- and near-field distributions are observed. (Poster paper)","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","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":"117298201","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":"Absorption spectrum of (ArKr)* in the ultraviolet","authors":"D. Kane, J. Eden","doi":"10.1364/ils.1986.thl31","DOIUrl":"https://doi.org/10.1364/ils.1986.thl31","url":null,"abstract":"Recent experiments reported by Pratt, Dehmer, and Dehmer have examined the electronic structure of NeXe, ArXe, and KrXe in the vicinity of the separated atom limits by resonantly enhanced multi photon ionization. However, little is known of the rare gas hetero-nuclear molecules near the potential minima of the Rydberg states. This paper describes experiments in which the absorption spectrum of the lowest electronic excited state of ArKr has been studied by inter-Rydberg laser spectroscopy. Specifically, excited Kr atoms are first produced by two-photon excitation of the Kr 6p[3/2]2 state at 103,363.4cm-1 in a mixture of 1040-TorrAr and 40-TorrKr(300 K pressures). Following the rapid relaxation of the 6p atoms into the 5s states, ArKr excited molecules are formed by three-body molecule collisions of Kr(5s) with two ground state Ar atoms. An adjustable time after the arrival of the first laser pulse (typically 700 ns), a dye laser beam excites the ArKr species to a higher-lying Rydberg state. Dissociation of the highly excited molecule is detectable by observing Kr atomic emission at 820 nm. A highly-structured band that is attributed to ArKr has been observed near 372 nm. Temporally resolved and pressure-dependent studies of this band show clearly that it is associated with neither Kr2 nor Ar2. The identification of this band as well as the remainder of the molecule’s UV absorption spectrum is discussed.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"10 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":"132938242","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":"High-resolution IR spectroscopy of ethylene dimers","authors":"R. Watts, K. Baldwin","doi":"10.1364/ils.1986.jfc8","DOIUrl":"https://doi.org/10.1364/ils.1986.jfc8","url":null,"abstract":"A differentially pumped free-jet expansion, together with a waveguide CO2 laser, has been used to measure the infrared predissociation spectrum of ethylene clusters near 950 cm-1. The CO2 laser has a pressure broadened tuning range of 240 MHz. We observe sharp transitions in association with many of the laser lines which activate the monomer C2H2 molecules in their v7 mode. By varying the concentration of C2H4 in a carrier gas, by changing the carrier gas, and by using both bolometric and mass spectrometric detection systems, we are able to confirm the findings of Snels et al.1 that there is fine structure in the ethylene dimer predissociation spectrum near 950 cm-1. The linewidths of all the observed features lie in the 15-20-MHz range, giving a lower limit on the pre-dissociation lifetime of ~ 10ns.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"39 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":"131300908","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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