Showing papers on "High harmonic generation published in 1982"
TL;DR: In this article, it was shown that in the process of harmonic generation in a non-linear crystal the fundamental mode becomes squeezed and when the squeezing is detected in the usual way by interference with a coherent field, the resulting field shows photon statistics that are narrower than poissonian by the same amount as the photons of the fundamental modes.
160 citations
TL;DR: The theory of second harmonic generation at a metal surface was developed in this paper, when surface plasmon-polaritons are resonantly excited by the incident electromagnetic field.
97 citations
TL;DR: In this paper, the amplitude and spectrum of the N th harmonic are calculated taking into account both the group velocity and group velocity dispersion, and conditions for group velocity matching in crystals and mixtures of metal vapors and gases are considered, together with their relation to phase velocity matching.
Abstract: Harmonic generation and frequency mixing in nonlinear media pumped by subpicosecond pulses are studied. The propagation and interaction of subpicosecond pulses in a dispersive medium is influenced by group velocity "walk through" and spreading of the light pulses. The amplitude and spectrum of the N th harmonic are calculated taking into account both the group velocity and group velocity dispersion. Conditions for group velocity matching in crystals and mixtures of metal vapors and gases are considered, together with their relation to the phase velocity matching. An example of using four-wave mixing to generate ultrashort pulses with tunable duration over a wide range by proper group velocity matching is discussed.
38 citations
TL;DR: In this article, it was shown experimentally and theoretically that only odd harmonics are generated for the ring oscillators with an odd number of stages, and the propagation delay t pd of the nth harmonic oscillation is given by t = n \cdot T/2N where T is the observed repetition period and N the number of stage.
Abstract: Harmonic generation is found with 101-stage ring oscillators. Harmonics have not been observed for the usual ring oscillators with a small number of stages. If one mistakes the higher harmonic generation for the fundamental, he obtains a wrong propagation delay which is shorter than the real one. It is shown experimentally and theoretically that only odd harmonics are generated for the ring oscillators with an odd number of stages. The propagation delay t pd of the nth harmonic oscillation is given by t_{pd} = n \cdot T/2N where T is the observed repetition period and N the number of stages. Computer simulation shows that a ring oscillator with an even number of stages can also oscillate if every inverter is the same, and that the oscillation decays if there is asymmetry in the inverter chain. If N is large and the effects of the deviations of the transistor parameters cancel one another, the harmonic oscillation that happens to be generated can continue.
36 citations
TL;DR: In this article, the growth of ion waves at a wave number of 2k/sub pump/ has been studied in a CO/sub 2/-laser-plasma interaction, by use of Thomson scattering.
Abstract: The growth of ion waves at a wave number of 2k/sub pump/ has been studied in a CO/sub 2/-laser--plasma interaction, by use of Thomson scattering. Time- and wave-number--resolved spectra have been obtained. Harmonic generation has been observed in the ion-wave spectrum. Saturation of the reflectivity is also observed. These results are consistent with nonlinearities in the ion wave affecting both the damping and the interaction length.
31 citations
TL;DR: A theory of second harmonic generation by optically active molecules in the presence of an external, static, electric field is presented in this article, where it is shown that the intensity of the second harmonic beam depends on the helicity of the incident radiation.
Abstract: A theory of second harmonic generation by optically active molecules in the presence of an external, static, electric field is presented. It is shown that the intensity of the second harmonic beam depends on the helicity of the incident radiation. Expressions for the intensity are derived using electric dipole, electric quadrupole, and magnetic dipole interactions, and the intensity dependence on helicity is given as a circular intensity differential ratio.
25 citations
TL;DR: Subharmonic generation has been observed during the propagation of deep-water capillary waves as mentioned in this paper, in agreement with the theory of degenerate resonant noncollinear three-wave interaction in a nonlinear, dispersive medium.
Abstract: Subharmonic generation has been observed during the propagation of deep‐water capillary waves. The observations are shown to be in agreement with the theory of degenerate resonant noncollinear three‐wave interaction in a nonlinear, dispersive medium.
19 citations
TL;DR: In this paper, the nonlinear properties of bulk and surface acoustic waves are described and the coupling with external, thermal, mechanical and electrical perturbations are analyzed for stable oscillators or sensor applications.
Abstract: Nonlinear properties of bulk and surface acoustic waves are described. Two classes of phenomena are distinguished: the nonlinear propagation of a finite amplitude wave and the nonlinear coupling of a small amplitude wave with the surrounding medium. Studies of the first one are harmonic generation, amplitude-frequency effect, intermodulation and convolution, mainly for signal processing applications. The coupling with external, thermal, mechanical and electrical perturbations are analyzed for stable oscillators or sensor applications.
17 citations
TL;DR: In this paper, a study of the multiplication of the frequency of picosecond pulses revealed a shift of the central frequency of the second harmonic spectrum dependent on the intensity of the fundamental frequency radiation.
Abstract: A study of the multiplication of the frequency of picosecond pulses revealed a shift of the central frequency of the second harmonic spectrum dependent on the intensity of the fundamental-frequency radiation It was found that the effect was associated with the cubic nonlinearity of the medium A theory of second harmonic generation was developed in the constant intensity approximation allowing for the quadratic and cubic nonlinearities
14 citations
TL;DR: In this article, the authors describe experimental results obtained with a packaged GaAs Schottky barrier diode in contact with a coaxial connector and placed across waveguides for bands Ka, V, E, W or F.
Abstract: This paper describes experimental results obtained with a packaged GaAs Schottky barrier diode in contact with a coaxial connector and placed across waveguides for bands Ka, V, E, W or F. Among the microwave sources used for calibration were 9 carcinotrons in the frequency interval 51–490 GHz. As soon as the frequency F is above the waveguide cut-off frequency, the different characteristics do not depend critically on the waveguide size for V, E, W and F bands. The video detection sensitivity, of several 100 mV/mW at 50 GHz and below, decreases as F−4 in the range 51–500 GHz. Coupling an X-band centimeter frequency via the coaxial connector and a millimeter frequency via the waveguide permits harmonic mixing in the diode. Between 36 and 490 GHz, the harmonic mixing number varies from 3 up to the very large value 40 with conversion losses from 18 to 88 dB. The minimum detectable signal in the 100 kHz band can be as low as −90 dBm at 80 GHz. A noticeable millimeter power is available at the waveguide output from injected centimeter power by harmonic generation. Starting for instance with 100 mW around 11.5 GHz, we have measured 0.1 mW at 80 GHz and 0.1 μW at 230 GHz. To illustrate the possibility of creating usable millimeter and submillimeter wave without heavy equipment (such as carcinotrons or millimeter klystron) we report spectroscopic experiments in Rydberg atoms. Resonances have been observed up to 340 GHz by harmonic generation (28th harmonic) from an X-band klystron).
12 citations
TL;DR: In this paper, a non collinear beam technique has been investigated numerically and experimentally, and it has been pointed out that an optimum separation angle can be found where tolerance on divergence of one beam is increased.
TL;DR: In this paper, a second harmonic plate is placed in the laser resonator in order to improve statistical and coherence properties of the lasing mode, and the level of both quantum and classical light fluctuations can be considerably decreased by multiple second harmonic generation in thin nonlinear plates, when filtering out the generated second harmonic radiation behind each plate.
TL;DR: In this paper, a linearly polarized wiggler is used to generate higher harmonic emission in free-electron laser systems, where the magnetic field is increased and the energy spread in the electron beam is reduced.
Abstract: Harmonic generation in the free-electron laser offers a possible means to extend the wavelength range of the device towards high frequency. Numerical solutions to the basic equations describing this process are shown for cw operation using a linearly polarized wiggler. Higher harmonic emission becomes enhanced as the magnetic field is increased and as the energy spread in the electron beam is reduced.
01 Jan 1982
TL;DR: In this article, the theory of the propagation of an ultrasonic wave of finite amplitude in a solid of trigonal symmetry has been developed, which does not yet include piezoelectric terms and leads one to predict pure mode propagation of both longitudinal and transverse waves along threefold symetry axis and in the x-direction in the basal plane.
Abstract: The theory of the propagation of an ultrasonic wave of finite amplitude in a solid of trigonal symmetry has been developed. In the t heory (which does not yet include piezoelectric terms), one finds that r etention of only linear terms leads one to predict pure mode propagation of both longitudinal and transverse waves along the threefold symetry axis and in the x-direction in the basal plane. Retention of the first set of nonlinear terms reveals that the transverse waves are no longer pure, but are coupled to the longitudinal modes. On the o ther hand, the longitudinal waves remain pure longitudinal but are coupled to their second harmonic (and higher harmonics). Nonlinearity parameters for propagation of longitudinal waves in the pure mode directions have been calculated. Preliminary measurements in a single crystal sample of LiNbOs have been made with the harmonic generation technique. fundamental and second harmonic are measured absolutely with a capacitive r eceiver. [loo] direction are given, and the effects of piezoelectricity on the measurements are discussed. Both Results for the
TL;DR: In this paper, the authors reported extensive measurements of radiation emitted from long Nb-Nb oxide-Pb overlap tunnel junctions with the lengths 0.5 mm and 1.0 mm having fundamental frequencies of 10 GHz and 5 GHz, respectively.
Abstract: Extensive measurements of radiation emitted from long Josephson junctions d.c.-current biased on zero-field and Fiske-steps are reported. The measurements were made in the band 8-10 GHz on long Nb-Nb oxide-Pb overlap tunnel junctions with the lengths 0.5 mm and 1.0 mm having fundamental frequencies of 10 GHz and 5 GHz, respectively. Depending on the fundamental frequency of the junction 1st or 2nd harmonic detection was employed. In the fundamental scheme the frequency fn vs. the d.c.-voltage Vn along the steps follows a modified Josephson voltage/frequency relation fn/Vn = 2e/nh, where n is the step-number n = 1, 2, 3,... for Fiske-steps and n = 2, 4, 6,... for zero-field steps. On a given step the frequency could be tuned (200-500 MHz) by varying the bias point. The linewidth was measured to be less than 5 kHz. All the observed phenomena are consistent with a novel unified dynamic bunched fluxon model applicable to both zero-field and Fiske-steps and are in good agreement with recent numerical solutions of the perturbed sine-Gordon equation with proper boundary conditions. Taking advantage of operation on higher order steps and strong harmonic generation the present upper frequency limit for the Josephson fluxon oscillator is above 200 GHz. The maximum power observed so far is only 5 pW, but the estimated available power is of the order 1 μW, which is quite sufficient to pump other Josephson devices.
TL;DR: In this article, a general solution describing electromagnetic wave propagation alone a transmission line periodically loaded with varactor diodes, with arbitrary terminal impedances, was obtained up to 3rd order in the frame of the Volterra functional method.
Abstract: A general solution describing electromagnetic wave propagation alone a transmission line periodically loaded with varactor diodes, with arbitrary terminal impedances, is obtained up to 3rd order in the frame of the Volterra functional method. Forward phase-matched 2nd harmonic generation with matched generator and load impedances is treated in detail. Design curves are given.
TL;DR: In this article, the authors used non-planar targets to estimate the optimum angle for resonance absorption from a single laser shot, and verified that this optimum angle increases with increasing laser intensity.
TL;DR: In this paper, it was shown that significant harmonic generation occurs in the converging portion of the beam and that the second harmonic beam focuses to a diffraction limited spot size which is smaller than the spot size of the fundamental beam by a factor of √.
Abstract: At the focus of a scanning acoustic microscope operating at 2.6 GHz, acoustic intensities in excess of 104 W/cm2 can be generated in a variety of liquids (e.g., water, liquid nitrogen, liquid argon). One consequence of operating at such high intensities is that the resolution of imaging is observed to significantly improve. This effect can be explained by considering the propagation of a finite amplitude focused Gaussian beam in a nonlinear medium. It is found that significant harmonic generation occurs in the converging portion of the beam and that the second harmonic beam focuses to a diffraction limited spot size which is smaller than the spot size of the fundamental beam by a factor of √. Upon passage through the focal region, the phase relationship of the second harmonic and fundamental changes such that a significant portion of the second harmonic power is converted back to the fundamental frequency. In this way, the high resolution information sensed by the second harmonic beam is communicated to t...
Patent•
29 Jun 1982TL;DR: In this paper, the authors used a single tunable dye laser to generate coherent, tunable vacuum ultraviolet radiation by third-harmonic generation using CO vapor, which was then used to eliminate the need for multiple-photon ionization.
Abstract: Carbon Monoxide vapor is used to generate coherent, tunable vacuum ultraviolet radiation by third-harmonic generation using a single tunable dye laser. The presence of a nearby electronic level resonantly enhances the nonlinear susceptibility of this molecule allowing efficient generation of the vuv light at modest pump laser intensities, thereby reducing the importance of a six-photon multiple-photon ionization process which is also resonantly enhanced by the same electronic level but to higher order. By choosing the pump radiation wavelength to be of shorter wavelength than individual vibronic levels used to extend tunability stepwise from 154.4 to 124.6 nm, and the intensity to be low enough, multiple-photon ionization can be eliminated. Excitation spectra of the third-harmonic emission output exhibit shifts to shorter wavelength and broadening with increasing CO pressure due to phase matching effects. Increasing the carbon monoxide pressure, therefore, allows the substantial filling in of gaps arising from the stepwise tuning thereby providing almost continuous tunability over the quoted range of wavelength emitted.
TL;DR: In this article, the authors investigated the second harmonic generation in cold inhomogeneous magnetoactive plasma by means of the mode coupling theory and showed that the generation from the upper-hybrid layer, where the pump field has a second-order singularity is negligible compared to the contribution of the wave-number matching region k(2ω0) = 2k(ω0), which can exist in the case of the extraordinary polarized pump wave.
Abstract: Second harmonic generation in cold inhomogeneous magnetoactive plasma is investigated by means of the mode coupling theory. It is demonstrated that the generation from the upper-hybrid layer, where the pump field has a second-order singularity is negligible compared to the contribution of the wave-number matching region k(2ω0) = 2k(ω0), which can exist in the case of the extraordinary polarized pump wave. Numerical results are presented, predicting the energy transfer efficiency ~ 10%.
TL;DR: In this paper, a comparison of three compositions of barium sodium niobate single crystals grown by the Czochralski method using Donets-1 apparatus with an improved stabilization of the output power of an hf oscillator was made.
Abstract: A comparison was made of three compositions of barium sodium niobate single crystals grown by the Czochralski method using Donets-1 apparatus with an improved stabilization of the output power of an hf oscillator. The absorption spectra were recorded. Measurements were made of the relative yield of the second harmonic of YAG:Nd laser radiation and of the absorption coefficient at the wavelengths of 0.63 and 1.15 μ. The best values of all three criteria were obtained for Ba2.09Na0.72Nb5.02O15 crystals.
12 Nov 1982-Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences
TL;DR: In this paper, the principles and operation of narrowbandwidth and mode-locked tunable dye lasers are described and the extension of their effective tuning ranges by harmonic generation and stimulated Raman scattering is discussed.
Abstract: The principles and operation of narrow-bandwidth and mode-locked tunable dye lasers are described and the extension of their effective tuning ranges by harmonic generation and stimulated Raman scattering is discussed. Methods of producing highpower ultraviolet radiation using excimer lasers and techniques for vacuum u.v. generation by frequency mixing are also described.