نتایج جستجو برای: harmonic orders
تعداد نتایج: 103855 فیلتر نتایج به سال:
The tendency for languages to use harmonic word order patterns—orders that place heads in a consistent position with respect to modifiers or other dependents—has been noted since the 1960s. As with many other statistical typological tendencies, there has been debate regarding whether harmony reflects properties of human cognition or forces external to it. Recent research using laboratory langua...
A systematic optimization study of quantum cascade lasers with integrated nonlinearity for third-harmonic generation is performed. To model current transport the Pauli master equation is solved using a Monte Carlo approach. A multi-objective particle swarm optimization algorithm is applied to obtain the Pareto front. Our theoretical analysis indicates an optimized structure with five orders of ...
Hyperbolic plasmonic metamaterials provide numerous opportunities for designing unusual linear and nonlinear optical properties. We show that the modal overlap of fundamental and second-harmonic light in an anisotropic plasmonic metamaterial slab results in the broadband enhancement of radiated second-harmonic intensity by up to 2 orders of magnitudes for TMand TE-polarized fundamental light co...
High-harmonic generation using ultrashort laser pulses with pulse durations 25 to 200 fs is studied theoretically and experimentally. We observe that the harmonic spectrum of argon taken with 25 fs laser pulses contains harmonics up to 20 orders higher than for 100 fs laser pulses with the same intensity. We show that this increase in harmonics is because the atom survives to higher laser inten...
We suggest the use of the refractive-index changes associated with the intersubband transitions in quantum wells for phase matching in nonlinear materials. An improvement in the conversion efficiency of mid-IR second-harmonic generation by almost 2 orders of magnitude over non-phase-matched bulk GaAs is predicted. We also show that the linear phase contributions of intersubband transitions used...
Diffracted surface second-harmonic radiation emerging in several orders has been observed from a periodically modulated monolayer of adsorbed dye molecules. The molecular grating was produced by laser-induced desorption in the field of two crossed beams. An elementary theory is presented that relates the characteristics of the second-harmonic diffraction pattern to the spatially varying propert...
We demonstrate a new high-order harmonic generation mechanism reaching the "water window" spectral region in experiments with multiterawatt femtosecond lasers irradiating gas jets. A few hundred harmonic orders are resolved, giving μJ/sr pulses. Harmonics are collectively emitted by an oscillating electron spike formed at the joint of the boundaries of a cavity and bow wave created by a relativ...
We report on broadband nonlinear optical (NLO) responses from a phase-change chalcogenide compound K(4)GeP(4)Se(12). Its glassy phase exhibits unusual second-harmonic generation (SHG) due to the preservation of local crystallographic order. The SHG efficiency of the glassy form can be boosted by more than 2 orders of magnitude by simple heat treatment. Strong SHG and third-harmonic generation f...
We use counterpropagating light to directly observe the coherent buildup of high harmonic generation in a hollow waveguide geometry. We measure, for the first time, coherence lengths for high photon energies that cannot be phase matched using conventional approaches. We also probe the transition through phase matching, the ionization level at which different harmonic orders are generated, and t...
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