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.

Nonlinear harmonic generation in high-gain free-electron lasers

Abstract: We reconsider the derivation of semianalytical expressions providing the most significant aspects of the high-gain free-electron laser dynamics. We obtain new expressions for the growth of the laser power, of the e-beam-induced energy spread, and of the higher-order nonlinearly generated harmonics. The procedure we employ, based on theoretical ansatz and fitting methods, allows the determination of crucial quantities like the expected harmonic output power and its dependences on the e-beam parameters.

Two-electron atoms in short intense laser pulses

Abstract: We discuss a method of solving the time-dependent Schrodinger equation for atoms with two active electrons in a strong laser field, which we used in a previous paper [A. Scrinzi and B. Piraux, Phys. Rev. A 56, R13 (1997)] to calculate ionization, double excitation, and harmonic generation in helium by shea laser pulses. The method employs complex scaling and an expansion in an explicitly correlated basis. Convergence of the calculations is documented and error estimates are provided. The results for He at peak intensities up to 10(15) W/cm(2) and wavelength 248 nm are accurate to at least 10%. Similarly accurate calculations are presented for electron detachment and double excitation of the negative hydrogen ion. [S1050-2947(98)00208-X].

Phase-matched periodic electric-field-induced second-harmonic generation in optical fibers

Abstract: Phase-matched electric-field-induced second-harmonic generation is demonstrated in single-mode germania-doped silica fibers. A periodic second-order nonlinearity is induced by a simple interdigitated electrode structure, which can be rotated to permit phase matching between all propagating modes. The most efficient mode interaction between HE11ω and HE112ω is achieved at 1.064 μm by using a Q-switched Nd+3:YAG laser. In principle, phase matching at any propagating wavelength is possible. This technique could be applied to planar as well as cylindrical waveguides and can be used with many non-χ(2) materials. The asymmetry in the applied electric field enhances the optical-field overlaps between modes of dissimilar orders, and this is also demonstrated. A conversion efficiency of 4.0 × 10−4% has been obtained in unoptimized devices. Device optimization is also discussed.

Generation of broadband mid-infrared pulses from an optical parametric amplifier

Abstract: We report on the direct generation of broadband mid-IR pulses from an optical parametric amplifier. Several crystals with extended IR transparency, when pumped at 800 nm, display a broad phase-matching bandwidth around 1 mum, allowing for the generation of idler pulses spanning the 3-5 mum wavelength range. Using LiIO(3), we produce 2muJ pulses tunable in the 3-4 mum range with bandwidth supporting 30-fs transform-limited duration.

Pulsed injection locking dynamics of passively mode-locked external-cavity semiconductor laser systems for all-optical clock recovery

Abstract: The performance characteristics of a pulse injection locked, passively mode-locked (PML) external-cavity semiconductor laser system for all-optical clock recovery are investigated in detail. It is important to characterize the clock recovery dynamics to understand the fundamental capabilities and limitations of the clock recovery system. It is experimentally shown that these devices offer robust clock recovery with low phase and amplitude noise, low injected data power requirements, large frequency locking bandwidth, large phase tracking bandwidth, short lockup time, long dephasing time and immunity to bit-pattern-effects. Harmonic clock generation and subharmonic clock generation are demonstrated for data-rate conversion applications.