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We demonstrate the efficiency enhancement of soft X-ray high-harmonic generation from Ar in the range of 40–200 eV using two-color (ω+3ω) mid-infrared pulses with relative phase control, which is in qualitative agreement with 3D simulations.
The various higher-harmonic orders generated in solids exhibit qualitatively different sensitivity to driver-pulse ellipticity, resulting from a different response of intraband and interband dynamics. Non-zero driver-pulse ellipticity permits harmonic cutoff extension and circularly polarized higher-harmonics.
We illuminate resonant and off-resonant plasmonic nanoparticles with few-cycle laser pulses and measure strong-field photoemission. Recording interferometric autocorrelations with the strong-field photocurrent, we study the response of the nanoparticle near-fields to ultrafast excitation.
Approaches towards a linear THz accelerator technology based on a novel multilayer waveguid structure, are discussed. Theoretical and first experimental results on laser based THz generation, guns, accelerators as well as compact X-ray sources based on those devices are presented.
Recently, we introduced an ab-initio time-dependent density-functional theory (TDDFT) framework that allows us to investigate the coupled interplay between the interband and intraband mechanisms of high-harmonic generation (HHG) from solids [1] without making a-priori model assumptions or strong approximations. Here, using HHG experiments on bulk silicon samples combined with TDDFT simulations, we...
We present a comprehensive study of laser pulse amplification of Ho:YLF regenerative amplifiers (RAs) with respect to operation regimes, gain dynamics, and output pulse stability. The findings are expected to be more generic than for this specific gain material. Operation regimes are distinguished with respect to pulse energy and the appearance of pulse instability, and are studied as a function of...
We describe cascaded difference-frequency generation (DFG) between multiple laser-lines generating terahertz pulses at >10% energy-conversion efficiency. DFG initiated by a laser-line and weak laser-seed rapidly cascades to self-generate multiple laser-lines and produce exponential terahertz growth.
The complete spatiotemporal dynamics in an octave-spanning oscillator is captured to further optimize its transform-limited pulse duration and beam profile for simultaneous short pulse generation and CEP locking.
We demonstrate experimentally the onset of cascaded optical parametric amplification (COPA) in periodically-poled lithium niobate. This technique permits narrowband terahertz wave generation beyond the Manley-Rowe limit.
We present a compact and robust cryogenically cooled Yb:YAG chirped pulse amplifier with 250W of average power at a repetition rate of 100 kHz with a near-diffraction limited beam quality.
A cryogenically cooled Yb:YAG amplifier with 4.7-ps laser pulses is employed to generate 100-GHz pulses in lithium niobate via optical rectification. We obtained a high efficiency ∼0.05% at 300 K, close to the theoretical prediction.
We demonstrate cascaded optical parametric amplification (COPA) as a promising pathway for efficient generation of THz-waves beyond the Manley-Rowe limit. The spectro-temporal characterization of this novel regime of parametric amplification is reported.
A family of approaches employing sequences of optical pump pulses, yielding energy conversion efficiencies in the 5–10% range, is introduced. A method to generate these sequences by cascaded optical parametric amplification of narrowband pulses is discussed.
THz driven electron acceleration is demonstrated and an approach towards a compact attosecond X-ray source based on THz driven relativistic electron beams is discussed. The source is suitable for coherent diffractive imaging and spectroscopy outrunning electronic damage.
We report on the theoretical and experimental spectro-temporal characterization of cascaded optical parametric amplification as a promising novel method for efficient THz wave generation.
The generation of few-cycle (sub-10-fs) pulses is important for optical frequency metrology, attosecond physics, and extreme nonlinear optics. There is much motivation to develop simple, robust, and inexpensive techniques for the amplification of these few-cycle pulses, especially to peak and average power levels exceeding the current limits of the Ti: sapphire laser technology. For instance, high-harmonic...
An algorithm for characterizing attosecond EUV pulses which is not bandwidth-limited, requires no interpolation of the experimental data, and makes no approximations beyond SFA while fully retrieving both the IR and EUV pulses is introduced.
We demonstrate a compact 290 fs, 0.5 mJ laser source at 2-μm wavelength generated from mJ-level 3.4-ps pulses from a fiber laser seeded Ho:YLF regenerative amplifier system via pulse compression in a gas-filled Kagome type HC-PCF.
In this work we demonstrate the design, fabrication and characterization of ultrafast, surface-plasmon enhanced Au nanorod photofield emitter arrays. We present a quantitative analysis of charge yield from plasmonic Au nanorod arrays fabricated by high-resolution electron beam lithography and triggered by 35 fs pulses of 800 nm light. We have accurately modeled both the optical field enhancement of...
Strong-field photoemission from plasmonic nanoparticles is demonstrated on the surface of a chip under ambient conditions. The photoemission shows a carrier-envelope phase-sensitive component with a 27 dB signal-to-noise ratio at a 0.78 Hz resolution bandwidth.
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