Topic
High harmonic generation
About: High harmonic generation is a research topic. Over the lifetime, 11694 publications have been published within this topic receiving 222650 citations. The topic is also known as: HHG.
Papers published on a yearly basis
Papers
More filters
TL;DR: A novel second harmonic generation (SHG) microscope that employs heterodyne detection by interfering the epi directed SHG from a sample with a reference crystal to extend the imaging depth as compared with direct detection.
Abstract: We describe a novel second harmonic generation (SHG) microscope that employs heterodyne detection by interfering the epidirected SHG from a sample with SHG from a reference crystal. In addition, the microscope provides complementary reflectance information based on optical coherence microscopy (OCM). The instrument features dual balanced detection to minimize the effect of source fluctuations, and polarization-sensitive detection to measure the nonlinear susceptibility of the sample. Interferometric detection can potentially improve the sensitivity and thus extend the imaging depth as compared with direct detection of SHG.
67 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 article, the second-harmonic conversion efficiency of two-dimensional hexagonally poled lithium niobate as a function of temperature and wavelength was measured using high-power nanosecond pulses.
Abstract: Using high-power nanosecond pulses, we measured the second-harmonic conversion efficiency of two-dimensional hexagonally poled lithium niobate as a function of temperature and wavelength. These results were compared with theoretical estimates and with measurements in one-dimensional periodically poled lithium niobate. We found that for a substantial range of parameters a two-dimensional noncollinear interaction has a broader tuning response than a one-dimensional collinear interaction. We also observed and characterized third- and fourth-harmonic generation processes in the same crystal.
67 citations
TL;DR: In this article, the authors analyzed high-order harmonic generation from low ionized laser plasma ablation in the presence of a strong radiative transition in plasma ions and showed that an integer multiple of the laser photon energy is resonant with this transition, a coherent superposition of ground and excited states having different parity is formed by pumping the excited state by HHG radiation.
Abstract: In order to explain the recently observed strong intensity enhancement of a single high-order harmonic we analyze high-order harmonic generation (HHG) from low-ionized laser plasma ablation in the presence of a strong radiative transition in plasma ions. If an integer multiple of the laser photon energy is resonant with this transition, a coherent superposition of ground and excited states having different parity is formed by pumping the excited state by HHG radiation. Resonant HHG from this superposition of states produces strong radiation at the plasma ions' transition frequency. The population of the excited state is increased and the stimulated emission becomes significant. The described physical picture of this process is illustrated by numerical examples related to the recent experiments.
67 citations
TL;DR: In this article, a nonlinear convolutional signal analysis for non-destructive testing of nonlinear systems using vibrations and elastic waves is proposed, which allows to extract the vibrational/acoustical responses of the system, at the excitation frequency and importantly, also at higher harmonics, with the help of a non linear convolution signal analysis.
Abstract: A method developed for the analysis of nonlinear systems is applied for the first time to non-destructive testing of diverse materials using vibrations and elastic waves. This method allows to extract the vibrational/acoustical responses of the system, at the excitation frequency and importantly, also at higher harmonics, with the help of a nonlinear convolution signal analysis. It is then possible to make use of the robust nonlinear resonance method together with the harmonic generation method in order to analyze the nonlinear elastic resonances of a sample at excitation frequency harmonics. Definitions of the nonlinear hysteretic parameters associated to higher harmonic resonances are provided. The bases of the signal analysis method are also described. A higher sensitivity to the presence of gradual damage compared to the classical nonlinear resonance method is demonstrated experimentally for diverse materials and configurations.
67 citations