Harmonic

About: Harmonic is a research topic. Over the lifetime, 44833 publications have been published within this topic receiving 495922 citations. The topic is also known as: overtone & partial.

Transverse Vibrations of Double‐Tapered Cantilever Beams

Abstract: The differential equation is developed from the Bernoulli‐Euler equation for the free vibrations of a double‐tapered cantilever beam. The beam tapers linearly in the horizontal and in the vertical planes simultaneously. From a computer solution of this equation, a table has been developed from which the fundamental frequency, second, third, fourth, and fifth harmonic can easily be obtained for various taper ratios. Charts are plotted for selected taper ratios in the vertical plane to show the effect of taper ratios on frequency.

Selective Enhancement of a Single Harmonic Emission in a Driving Laser Field with Subcycle Waveform Control

Abstract: We experimentally demonstrate a robust scheme to select a single high-order harmonic among the harmonic comb by using a driving laser field with subcycle waveform control, which is synthesized by the fundamental 800 nm laser pulse and two controlling laser pulses at 400 and 267 nm with perpendicular polarizations. By controlling the relative phase among the pulses of different colors, a single high-order harmonic is selectively enhanced while the adjacent harmonics are greatly suppressed with the intensity contrast increased by more than 1 order of magnitude and the peak intensity enhanced simultaneously by more than 2 orders of magnitude compared to the case by using only the fundamental 800 nm laser pulse. Such phenomena can be mainly attributed to the intra-atomic phase matching realized with the sub-cycle waveform controlled field.

Enhanced four-wave mixing in a hollow-core photonic-crystal fiber.

Abstract: Hollow-core photonic-crystal fibers are shown to substantially enhance four-wave mixing (FWM) of laser pulses in a gas filling the fiber core. Picosecond pulses of Nd:YAG fundamental radiation and its second harmonic are used to generate a signal at the frequency of the third harmonic by the FWM process 3⍵=2⍵+2⍵-⍵ . The efficiency achieved for this process in a 9-cm-long, 13-mu;m -hollow-core-diameter photonic-crystal fiber, designed to simultaneously transmit a two-color pump and the FWM signal, is shown to be ~800 times higher than the maximum FWM efficiency attainable with the same laser pulses in the tight-focusing regime.

Independently Controllable Dual-Band Bandpass Filters Using Asymmetric Stepped-Impedance Resonators

Abstract: This paper presents a dual-band bandpass filter with independent switchability of each passband. By taking advantage of harmonic ratio of asymmetric stepped-impedance resonators, 2.4- and 5.2-GHz resonators are designed. The second resonance of 2.4-GHz resonators is designed to be suppressed by a transmission zero created by extended feed lines. To achieve a wide upper stopband, 5.2-GHz resonators are designed with a scheme that the second peak of these resonators would not appear at a frequency lower than a third peak of 2.4-GHz resonators. Several design graphs for deciding both geometric parameters and transmission zeros are plotted by using the information obtained from electromagnetic simulations. While extracting coupling coefficients between resonators, an external quality factor at 50-Ω port is fixed to determine the precise transmission zeros. Two kinds of feed lines, such as a hook type and a spiral type, are developed, and spiral-type feed lines are chosen for realizing switchable filters. By controlling p-i-n diodes, four states of switchable dual bands are clearly presented in simulations and experiments.