{"title":"Ultrasensitive coherent Raman technique with picosecond lasers","authors":"M. Schauer, M. Pellin, B. Biwer, D. Gruen","doi":"10.1063/1.98202","DOIUrl":"https://doi.org/10.1063/1.98202","url":null,"abstract":"The sensitivity of the Raman-induced Kerr effect is greatly enhanced through the use of picosecond lasers. Experiments in dilute solutions of benzene indicate that sensitivity at the monolayer level is achievable. Applications to transparent media, to fluorescing samples, and to in situ measurements of electrode surfaces are discussed. Comparisons are made to surface-enhanced Raman spectroscopy and to coherent anti-Stokes Raman spectroscopy.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1987-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131978556","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":"Radiative trapping effects in ruby: 77 K to 300 K","authors":"M. Birnbaum, C. Fincher, J. Machan, M. Bass","doi":"10.1063/1.36872","DOIUrl":"https://doi.org/10.1063/1.36872","url":null,"abstract":"The fluorescent decay of the 2\u0000 E\u0000 level of the Cr3+ over the range of 77 K to 300 K has been studied in experimental arrangements pro viding strong trapping of the O-phonon lines. At 300 K, rubies as large as 2.5 cm diameter by 28 cm length were used, packed in highly reflective BaSO4 powder to provide adequate trapping of the O-phonon fluorescence. The measurements resulted in the explicit determination of the lifetime vibronic transitions and the O-phonon decay rate.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1986-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130972951","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 pulse sequence induced control of selectivity of reactions","authors":"D. Tannor, R. Kosloff, S. Rice","doi":"10.1063/1.451542","DOIUrl":"https://doi.org/10.1063/1.451542","url":null,"abstract":"We present a novel approach, suggested by Tannor and Rice, to the control of selectivity of photochemical reaction products. The central idea is that in a two-photo or multiphoton process that is resonant with an excited electronic state, the resonant excited state potential energy surface can be used to assist chemistry on the ground state potential energy surface. By controlling the delay between a pair of ultrashort (femtosecond) laser pulses, it is possible to control the propagation time on the excited state potential energy surface. Different propagation times, in turn, can be used to generate different photochemical products. There are many cases for which selectivity of product formation should be possible using this scheme. Our examples show a variety of behaviors ranging from virtually 100% selectivity to poor selectivity, depending on the nature of the excited state potential energy surface. Branching ratios obtained using a swarm of classical trajectories are in good qualitative agreement with full quantum mechanical calculations.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"375 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1986-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115475541","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":"Morphology-dependent resonances associated with stimulated processes in microspheres","authors":"S. C. Hill, R. Benner","doi":"10.1364/JOSAB.3.001509","DOIUrl":"https://doi.org/10.1364/JOSAB.3.001509","url":null,"abstract":"The density of morphology dependent resonances (MDRs) of microspheres is much larger than the density observed in typical resonance spectra. It is large enough to be consistent with observations1 of multiorder Stokes emission in the stimulated Raman scattering from microspheres. The question of whether MDRs having extremely large cavity Q (> 1010 if the spheres are lossless) contribute to the optical feedback in real spheres is discussed. Only the low-order very narrow linewidth MDRs have angle-averaged intensities that are consistent with photographs2 of the light emission from lasing spheres. Although the integrated area under the scattered field coefficients tends to zero as the cavity Q increases, the area under the internal field coefficients (which are proportional to the intensities of stimulated processes) gradually increases as the cavity Q increases. Hence it would appear that the very high Q MDRs provide the optical feedback for stimulated processes in microspheres. When a sphere is illuminated with a high intensity laser beam a nonuniform refractive index may be induced which may so perturb or couple the low-order MDRs that it may not be appropriate to ascribe the optical feedback to the MDRs of homogeneous spheres.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"61 27","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1986-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114005658","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":"XUV laser Stark spectroscopy of Xe autoionizing Rydberg states","authors":"W. Ernst, T. Softley, L. Tashiro, R. Zare","doi":"10.1063/1.36722","DOIUrl":"https://doi.org/10.1063/1.36722","url":null,"abstract":"Tunable coherent radiation between 90 and 110 nm is generated by frequency tripling the output of a pulsed frequency-doubled dye laser in a free jet of rare gas atoms.1 The XUV beam is crossed by an atomic Xe beam to observe single-photon transitions from the ground state of Xe to the autoionizing Rydberg series in the vicinity of the second ionization limit. A Stark field is applied in the interaction region. At moderate field strengths (>100 V/cm) wave functions with different / mix and transitions to the 5p5(2P1/2) np series are observed in addition to the ns and nd series. The line intensities and shifts have been investigated for 0 < E < 2 kV/cm. As the third harmonic XUV beam is collinear with the high power fundamental UV laser radiation, the spectroscopy of many other species is obscured by UV multiphoton absorption processes. We have studied schemes for separating XUV and UV and will discuss the application of a dichroic beam splitter.2","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"134 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1986-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116567263","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. Gould, G. Ruff, P. Martin, J. Picqué, R. Stoner, D. Pritchard
{"title":"Experimental study of light forces on atoms: diffraction and diffusion","authors":"P. Gould, G. Ruff, P. Martin, J. Picqué, R. Stoner, D. Pritchard","doi":"10.1364/ils.1986.wc6","DOIUrl":"https://doi.org/10.1364/ils.1986.wc6","url":null,"abstract":"We have observed both diffractive and diffusive regimes in the transfer of momentum to an atomic beam by a standing-wave radiation field. The momentum transfer was measured by passing a well-collimated beam of sodium atoms through a focused standing-wave laser waist. A narrow velocity distribution beam was obtained by utilizing a supersonic expansion and a two-state system was realized by optically pumping the beam prior to the interaction. The transverse momentum transferred to the atomic beam by the radiation field was measured by scanning a detector downstream from the interaction. The overall momentum resolution of the apparatus is less than the momentum of a single photon. The transition from diffractive to diffusive behavior is associated with an increase in the average number of spontaneous decays occurring during the interaction. In the diffractive regime, spontaneous decay is insignificant and momentum transfer proceeds by pairs of absorption/stimulated emission processes. This produces momentum exchange quantized in even multiples of photon momentum, the so-called Kapitza-Dirac effect; the deflection patterns show oscillatory structure. In the diffusive regime, spontaneous decay is important and causes fluctuations in the radiative forces. In addition, the recoil distribution associated with spontaneous decay results in a washing out of the diffraction peaks associated with stimulated processes, resulting in a smooth deflection pattern.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1986-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117299074","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. Lai, B. Chai, M. Long, M. Shinn., J. Caird, J. Marion, T. R. Staver
{"title":"ScBO3:Cr—a new room temperature near-infrared tunable laser","authors":"S. Lai, B. Chai, M. Long, M. Shinn., J. Caird, J. Marion, T. R. Staver","doi":"10.1364/ASSL.1986.WB10","DOIUrl":"https://doi.org/10.1364/ASSL.1986.WB10","url":null,"abstract":"We report the first Cr3+ laser in a borate host crystal. The free-running laser wavelength was 843 nm in a nearly concentric laser cavity pumped by a krypton-ion laser at 647.1 nm. With a single element birefringent filter, a tuning range of 787-892 nm was measured using the first optically clear crystal. The output power slope efficiency was 29% lasing at 848 nm with an output coupler of 1.78% transmission. The laser round trip loss, including a possible excited state absorption, was calculated to be 1.3% cm. Spectroscopic measurements indicated that the material was clear of absorption loss in the lasing spectral region, and the relative fluorescence efficiency for the entire Cr absorption band in the visible region was nearly unity. The fluorescence lifetime at room temperature was 115µS. A study of lifetimes vs temperatures showed that the multiphonon relaxation process had an onset temperature of ~ 340 K. The peak emission cross section was calculated to be 1.2 × 10−20 cm2 at 873 nm for the c-axis polarization.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1986-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124599328","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}
J. Bowers, A. Srivastava, C. Burrus, M. DeWinter, M. Pollack, J. Zyskind
{"title":"High-speed GalnAsSb/GaSb PIN photodetectors for wavelengths to 2.3 μm","authors":"J. Bowers, A. Srivastava, C. Burrus, M. DeWinter, M. Pollack, J. Zyskind","doi":"10.1049/EL:19860096","DOIUrl":"https://doi.org/10.1049/EL:19860096","url":null,"abstract":"Photodetectors are needed for future communications systems utilizing novel mid-infrared fiber materials with extremely low predicted losses in the 2–4-μm wavelength range. We report improved performance of front-illuminated GalnAsSb/GaSb PIN homojunction photodiodes1 that operate with high speed and high quantum efficiency at room temperature. The photodiodes consist of a Zn-diffused homojunction 0.3 μm below the surface of a 3-μm thick layer of n-type Ga0.82ln0.18As0.17Sb0.83. This layer was grown by liquid-phase epitaxy on a GaSb substrate and doped with Sn to a level of n = 2.5 × 1015cm−3. A partial metallization of the 100-μm diam mesa surface allows for front illumination of the chips, which are packaged as described in Ref. 2. The external quantum efficiency without antireflection coating is constant at 55–65% for wavelengths up to 2.2 μm. At 1.06 μm the impulse response of the detector has a FWHM of 110 ps. At 1.3 μm it responds to pseudorandom modulation at bit rates up to 4 Gbit/s.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1986-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115487086","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}
J. Stańco, G. Śliwiński, J. Konefal, P. Kukiełło, G. Rabczuk, Z. Rozkwitalski, R. Zaremba
{"title":"Investigation of a transverse-excited high-power CO2 laser","authors":"J. Stańco, G. Śliwiński, J. Konefal, P. Kukiełło, G. Rabczuk, Z. Rozkwitalski, R. Zaremba","doi":"10.1364/ils.1986.thl7","DOIUrl":"https://doi.org/10.1364/ils.1986.thl7","url":null,"abstract":"Investigations of a high-power transverse-flow transverse-discharge closed-cycle cw CO2 laser, designed as a laboratory facility primarily for materials processing research, are reported. A self-sustained dc electric discharge between a multipin cathode (tungsten) and a planar anode (polished copper) has been used forexcitation of the working medium, a mixture of CO2, N2, and He. The discharge volume is 5 dm3. A controllable-speed centrifugal compressor circulated the gas at a pressure of ~ 80 kPa, with the mass flow rate reaching 0.5 kg s-1. The specific power per unit mass flow amounts to 200 kW/kg s-1. The discharge characteristics have been measured in various flow conditions to evaluate the effect of flow conditioning devices on the discharge stability. Various multipass unstable optical resonator configurations have been adopted based on previous numerical analyses. Measurements of small-signal gain distribution along the discharge channel (with a maximum of 1 m–1) allowed optimization of the resonator position relative to the discharge. The dependence of the output power on the electric power dissipated in the discharge was measured. For a two-pass resonator (M = 1.8 kanigen mirrors) with one amplifying pass, the maximum output beam power was 4.4 kW at an electro-optical efficiency of 10%. The beam divergence was ~2 times larger than the diffraction-limited value. This allowed satisfactory tests of laser welding and cutting. (Poster paper)","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","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":"124278748","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":"Applications of shaped laser pulses to state-selective excitation and measurement of gas phase collisional dynamics","authors":"M. Banash, J. Bates, C. P. Lin, W. Warren","doi":"10.1364/ils.1986.we4","DOIUrl":"https://doi.org/10.1364/ils.1986.we4","url":null,"abstract":"We discuss experimental applications of specific phase and amplitude modulated laser pulse shapes. Electronic transitions in real molecules generally do not have a well-defined Rabi frequency because of the distribution of the orientation of the transition dipole, and because the density of states for all but the very simplest molecules causes many Doppler broadened transitions (including hyperfine components) to overlap. Crafted pulse shapes generate complete population inversions regardless of Rabi frequency, as well as provide a uniform inversion over the pulse bandwidth.1 These experiments directly observe population transfer between frequency ranges by giving two different frequency π pulses at different times—the use of crafted pulses increases signal to noise by now inverting the entire Rabi distribution. Experimental modifications which select a single velocity range in an arbitrarily complex molecule while retaining the other advantages of pulse shaping are presented, and the velocity dependence of fluorescence and coherence lifetimes in molecular gases is analyzed.2 Applications to monitoring velocity-changing collisional dynamics and generating large vibrational population inversions in l2 are presented, as will experimental methods to extend these sequences to more complex molecules, where velocity selection and frequency resolution are not equivalent.","PeriodicalId":422579,"journal":{"name":"International Laser Science Conference","volume":"106 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":"122424126","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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