Showing papers on "High harmonic generation published in 1980"
Book•
01 Jan 1980
TL;DR: In this article, a theory of the nonlinear optical sensitivity is presented, and the propagation of plane waves in a nonlinear medium is discussed, including the use of Raman-Resonant Four-Wave Processes in free Molecules.
Abstract: 1. Introduction.- 2. Theory of the Nonlinear Optical Susceptibility.- 3. Propagation of Plane Waves in a Nonlinear Medium.- 4. Sum Frequency and Harmonic Generation.- 5. Stimulated Electronic Raman Scattering.- 6. Raman-Resonant Four-Wave Processes.- 7. Nonlinear Optical Processes in Free Molecules.- 8. Some Miscellaneous Topics.- Appendix: Units for Non-Linear Optical Susceptibilities.- Universal Constants.- List of Major Symbols and Acronyms.- References.
308 citations
TL;DR: In this article, the authors reported an efficient conversion from 1.054 μm to 0.35 μm by third harmonic generation in two Type II KDP crystals, achieving energy conversion efficiencies of up to 80% under conditions applicable to large glass laser systems.
130 citations
TL;DR: In this article, a tripling configuration was used in which the fundamental beam was incident upon the first of two KDP Type II crystals linearly polarized at an angle of tan−1 1/√2 to the ordinary direction.
87 citations
Patent•
08 Dec 1980TL;DR: In this article, a step recovery diode operated in a double pulse mode for each period of the cycle of the input frequency signal was selected to provide stable operation, and bias circuitry for the diode and impedance characteristics of input and output bandpass filters were selected.
Abstract: A frequency multiplier which employs a step recovery diode operated in a double pulse mode for each period of the cycle of the input frequency signal provides efficient and high order harmonic generation. The bias circuitry for the diode and impedance characteristics of the input and output bandpass filters are selected to provide stable operation.
67 citations
TL;DR: In this paper, double resonance enhancements of the elements of the third-order nonlinear susceptibility (χ(3), which describe four-wave sum mixing into the vacuum ultraviolet (VUV), were investigated.
Abstract: Two and three‐photon spectra have been obtained by single and double resonance enhancements of the elements of the third‐order nonlinear susceptibility (χ(3)), which describe four‐wave sum mixing into the vacuum ultraviolet (VUV). Results are reported for nitric oxide, in which the A 2Σ+−X 2Π transition is utilized for two‐photon resonant enhancement in χ3ω(3). Relative intensities of the recorded rotational structure agreed well with the predictions of theory based on multiphoton transition probabilities, with the exception of cases where there was accidental double resonant enhancement of χ(3), occurring through both two and three‐photon transition probabilities. Finally, in studies designed to explore double resonance effects in χ(3)(2ω1+ω2), two lasers were used to probe simultaneous contributions from the A 2Σ+ and M 2Σ+ states of NO. Signals were further enhanced by a factor of 103 to values as large as 10−4 of the input dye laser intensity.
44 citations
TL;DR: In this paper, the results of theoretical and experimental studies of effects in the interaction of powerful laser radiation with liquid crystals (LC) are reviewed, and the relation between the symmetry of the molecules forming the LC phase and the symmetric nonlinear susceptibilities is analyzed; a special role is reserved for the spatial dispersion of LC susceptibility.
Abstract: The results of theoretical and experimental studies of effects in the interaction of powerful laser radiation with liquid crystals (LC) are reviewed. Attention is drawn to two aspects of these studies: 1) use of LC materials in nonlinear optical devices (specifically, the nonlinear optics of LC); 2) the use of laser methods to study the LC state of matter (nonlinear spectroscopy of LC). Specific aspects of optical harmonic generation effects, induced Raman scattering, and the self-action of powerful laser beams are discussed in detail. LC restructuring effects under the action of coherent radiation are described. The relation between the symmetry of the molecules forming the LC phase and the symmetry of macroscopic nonlinear susceptibilities is analyzed; a special role is reserved for the spatial dispersion of LC susceptibility, which has a bearing, in particular, on the possibility of generation of even optical harmonics and on the possibility of specific light self-action modes. Recent experiments on second-harmonic generation in nematic LC, on measurement of LC relaxation parameters in the pretransition range, and on the nonstationary self-focusing effect are described, as well as determination of higher elements of the orientation distribution function of LC molecules from induced-scattering characteristics.
41 citations
TL;DR: In this paper, a simplified treatment of sound production in musical instruments driven by air jets is given, which is sufficiently explicit that semiquantitative predictions can be made about the effects of certain variables upon the harmonic structure of the sound produced.
Abstract: A simplified treatment is given of the mechanism of sound production in musical instruments driven by air jets, which is sufficiently explicit that semiquantitative predictions can be made about the effects of certain variables upon the harmonic structure of the sound produced. In particular it is found that the amplitude of the even harmonics, generally, and of the second harmonic, particularly, is quite critically dependent upon the offset of the pipe lip from the symmetry plane of the jet. A completely symmetrical relationship (zero offset) reduces the generated amplitude of the second harmonic by a large factor. Experimental results with an adjustable organ pipe are found to confirm these predictions. The implications of these results for the voicing of organ pipes and recorders and for subtle tonal variation in flute playing are briefly discussed.
35 citations
TL;DR: The use of rare gas halide lasers for generating tunable XUV radiation through harmonic generation and frequency mixing and third- to ninth-order nonlinear interactions is discussed.
Abstract: The generation of coherent XUV radiation through harmonic generation and frequency mixing is described. Results that have been obtained using third- to ninth-order nonlinear interactions are summarized. The use of rare gas halide lasers for generating tunable XUV radiation is discussed.
30 citations
TL;DR: In this paper, a molecular theory of harmonic generation in free molecules is developed using the principles of quantum electrodynamics, and emphasis is placed on the rotational average which is required to account for the random molecular orientations in the pump beam.
Abstract: A molecular theory of harmonic generation in free molecules is developed using the principles of quantum electrodynamics. A Cartesian tensor formalism is employed and emphasis is placed on the rotational average which is required to account for the random molecular orientations in the pump beam. It is demonstrated that even harmonics are forbidden to all orders of the multipolar interaction Hamiltonian and in the appendix a new relation involving the rotational average of an arbitrary rank Cartesian tensor is presented.
29 citations
TL;DR: In this paper, the angular divergence of optical second harmonic generation in rat-tail tendon reveal a very narrow forward peak, which implies the existence of coherent order and, together with the demonstration of nonlinear susceptibility components d 33 and d 32, confirms prior indications that the tendon is polar.
20 citations
TL;DR: In this article, the authors studied the second-harmonic generation of upper-hybrid electromagnetic radiation in an inhomogeneous plasma and showed that the maximum contribution for harmonic generation comes from the vicinity of the upper hybrid layer, and the harmonic conversion efficiency turns out to be \ensuremath{sim} 0.1% at the power densities
Abstract: Employing the fluid model for the nonlinear response of electrons, we have studied the phenomenon of second-harmonic generation of upper-hybrid electromagnetic radiation in an inhomogeneous plasma. In the case of laser-pallet fusion, the maximum contribution for harmonic generation comes from the vicinity of the upper-hybrid layer, and the harmonic conversion efficiency turns out to be \ensuremath{\sim}0.1% at the power densities \ensuremath{\sim}${10}^{14}$ W/${\mathrm{cm}}^{2}$ (C${\mathrm{O}}_{2}$ laser), the same order as observed experimentally. In the case of electron cyclotron heating experiments of tokamak, a strong second harmonic must be generated at the cyclotron resonance layer. The wave-number-matching condition could be satisfied in a tokamak, which adds to the conversion efficiency.
TL;DR: In this paper, the nonlinear response of a metal to optical fields is derived for a hydrodynamic model of electron dynamics, and the results are used to analyse recent experiments on harmonic generation from a prism-silver film-α quartz sample.
TL;DR: In this article, an electron density of ∼ 10 20 cm -3 was found to occur at power levels notably higher than inferred from the ocular observation of broad band luminescence.
TL;DR: In this article, the second, third and forth harmonic of mode-locked iodine laser pulses were reported and the energy conversion efficiencies relative to the iodine laser were 30, 6% and 5% respectively.
TL;DR: In this paper, the second harmonic (SH) generation in a laser produced plasma (NdYAG laser with wavelength 1.06 μm, pulse duration 30 ps, intensity 10 13 Wcm -2 ) was investigated experimentally as a function of polarization and angle of incidence of the laser beam.
TL;DR: In this paper, the authors theoretically treated the two-pass optical second-harmonic generation for analyzing the effects of the walkoff, the absorption in the nonlinear crystal and the beam radius of the fundamental laser.
Abstract: The two-pass optical second-harmonic generation is theoretically treated for analyzing the effects of the walk-off, the absorption in the nonlinear crystal and the beam radius of the fundamental laser. Computational results show the range of the crystal length where a higher second-harmonic power is obtained in the two-pass system than in the one-pass one.
TL;DR: In this paper, the influence of focusing on third, fourth, and fifth harmonic generation was analyzed for both direct and cascade processes taking place due to lower-order nonlinearities.
Abstract: An analysis is made of the influence of focusing on third, fourth, and fifth harmonic generation allowing for both direct and cascade processes taking place due to lower-order nonlinearities. It is found that as the focusing parameter increases under conditions of optimized wave mismatch, the fourth and fifth harmonic powers increase monotonically. It is also shown that in the case of phase-matched cascade processes, the harmonic power is highest for focusing on one of the faces rather than at the center of the nonlinear medium.
TL;DR: In this article, a model that relates the length and density of microcracks to the amplitude of a SAW harmonic signal is described, and an associated coefficient of generation efficiency for the second harmonic amplitude is derived.
Abstract: Harmonic generation of surface acoustic waves (SAW) is shown to be a useful tool for the detection of the initiation of surface cracks during fatigue of high strength aluminum alloys. A model that relates the length and density of microcracks to the amplitude of a SAW harmonic signal is described, and an associated coefficient of generation efficiency for the second harmonic amplitude is derived. A correlation between experimentally measured harmonic amplitude and remaining fatigue life is then demonstrated, which allows the mean remaining fatigue lifetime to be estimated to within 5% over the last 50% of the fatigue life for an Al 7075 alloy if the cyclic stress amplitude, but not the duration of fatigue, is known.
01 Aug 1980
TL;DR: In this article, the dependence of the multiplier characteristics on carrier density, device length and frequency is analyzed for two models of GaAs differing in the strength of the intervalley scattering rate.
Abstract: Computer simulations of n+-n-n+ transferred-electron devices predict a frequency multiplier mode with favourable properties as a power source for the millimetre band. The mode is related to the l.s.a. ocillator, but waveform distortion allows operation to a considerably higher frequency. Second-harmonic generation is much more efficient than generation of higher harmonics. The dependence of the multiplier characteristics on carrier density, device length and frequency are analysed for two models of GaAs differing in the strength of the intervalley scattering rate. Comparison indicates that strong intervalley scattering leads to a higher frequency limit. Estimates of the power and impedance parameters of devices are made as precursors to circuit design.
TL;DR: In this article, the authors studied the effect of hot electron nonlinearity in Si-inversion layers at 77 K in the presence of a large high frequency signal on a drifted Maxwellian model and showed that the third harmonic content increases with increase in field amplitude but decreases to negligible values for frequencies of about 1000 GHz.
Abstract: Harmonic generation due to hot electron nonlinearity in Si-inversion layers at 77 K in the presence of a large high frequency signal is studied on a drifted Maxwellian model. The third harmonic content increases with increase in field amplitude but decreases to negligible values for frequencies of about 1000 GHz.
TL;DR: In this paper, it was shown that a second-harmonic field may be generated, but only in a TM om mode; this then indicates that harmonic generation and mode conversion act as simultaneous processes.
Abstract: Using Hertz potentials it is possible to analyze the problem where a dominant HE 11 fundamental excites a nonlinear line of material on the axis of a fiber. For a nonlinear line with a specified crystal symmetry of \bar{4}3 m, it is shown that a second-harmonic field may be generated, but only in a TM om mode; this then indicates that harmonic generation and mode conversion act as simultaneous processes. Phase matching constraints are discussed and it is shown that the field buildup properties are analogous to those found in rectangular geometries.
Journal Article•
Patent•
27 Oct 1980TL;DR: In this paper, the authors present an apparatus for providing second harmonic generation from a single beam in an isotropic medium, where the photons in the laser beam have an energy which is substantially equal to one-half the energy difference between the first and second levels.
Abstract: The present invention relates to an apparatus for providing second harmonic generation from a single beam in an isotropic medium. An isotropic medium having a two-photon transition between a first level and a second level with a quadrupole moment therebetween is exposed to a beam of laser radiation. The photons in the laser beam have an energy which is substantially equal to one-half the energy difference between the first and second levels.
01 Mar 1980
TL;DR: A submitted manuscript is the author's version of the article upon submission and before peer-review as discussed by the authors, and the final published version features the final layout of the paper including the volume, issue and page numbers.
Abstract: • A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers.
TL;DR: In this paper, an analysis of the finite amplitude acoustic waves induced by harmonic vibration of a region in an infinite planar boundary is presented. Butler et al. employed a perturbation formulation to obtain the first-order and second-order terms in the velocity potential.
Abstract: This is an analysis of the finite amplitude acoustic waves that are induced by harmonic vibration of a region in an infinite planar boundary. Only situations leading to two‐dimensional waves in inviscid fluids are considered. A perturbation formulation is employed to obtain the first‐order (linear) and second‐order (first nonlinear correction) terms in the velocity potential. A Fourier transform leads to a description of the linear potential in terms of propagating and evanescent nonuniform planar waves occurring in a continuous spectrum of transverse wavenumbers. The linear solution is used to evaluate the source terms for the second‐order potential. The portion of the latter which exhibits cumulative growth of higher harmonics is evaluated by a method based on the principle of stationary phase. The results indicate that harmonic generation at a specific transverse wavenumber is primarily independent of the response associated with other wavenumbers.
TL;DR: In this article, the strong RF voltage fluctuations associated with the sudden onset of DC voltage near the critical current in a clean superconducting point contact were investigated and the mechanism of efficient harmonic generation was discussed briefly.
Abstract: Spectral analyses are carried out on the strong RF (1.2-1.4 GHz) voltage fluctuations associated with the sudden onset of DC voltage near the critical current in a "clean" superconducting point contact. The strong RF voltage is concluded to arise from the remarkably efficient frequency conversion effects of weak external low-frequency (below 100 MHz) interference. Strong higher harmonics of intentionally-applied signals of about 250 and 90 MHz are observed up to 2 GHz. The mechanism of efficient harmonic generation is discussed briefly.
Journal Article•
TL;DR: Intercavity second harmonic generation effects on beats of opposing waves was studied in this paper, where the authors considered the effects of the second harmonic second wave on the beat of the opposing wave.
Abstract: Intercavity second harmonic generation effects on beats of opposing waves is studied. (AIP)
01 Jun 1980
TL;DR: In this article, the second-harmonic generation efficiency in II-VI compound semiconductors at 77 K under high-field condition has been calculated using a nonlinear analytical approximation for the velocity-field characteristics.
Abstract: The second-harmonic generation efficiency in II-VI compound semiconductors at 77 K under high-field condition has been calculated using a nonlinear analytical approximation for the velocity-field characteristics. It is found that the harmonic generation efficiencies are considerably higher than the corresponding values for elemental semiconductors.
01 Jan 1980
TL;DR: In this paper, a discussion of some of the physics and applications of the nonlinear optical properties of solids is presented. But the main focus of the paper is on the propagation and interaction of three electromagnetic waves in a nonlinear medium.
Abstract: The aim of this chapter is a discussion of some of the physics and applications of the nonlinear optical properties of solids. It begins with a review of electromagnetic wave propagation in solids and a derivation of the familiar linear relation between dielectric polarization and electric field. A more realistic anharmonic oscillator model is next introduced and this is shown to yield a polarization that is a nonlinear (specifically, a quadratic) function of the electric field. A physical picture of the nonlinear polarization and some solid state physics factors affecting the magnitude of the nonlinear susceptibility are also given. The central topic of the chapter is the propagation and interaction of three electromagnetic waves in a nonlinear medium. This results in a set of equations describing the spatial variation of the electric fields of these waves as they move through the crystal. Finally, these equations are used to discuss several applications of nonlinear solids. These are optical second harmonic generation, frequency mixing and up-conversion, and parametric amplification of optical signals.