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We demonstrate pulse burst generation method based on the Vernier effect. The pulse burst with controllable amplitudes and phases is formed using a femtosecond oscillator and regenerative amplifier cavity that have slightly different round trip times. This operation mode can be used for the purposes of coherent pulse stacking, rapid material miroprocessing and rapid scan spectroscopy.
Here we present a coherent pulse stacking approach for up-scaling energy of a solid-state femtosecond chirped pulse amplifier. We demonstrate pulse splitting into four replicas, amplification in a specially designed regenerative amplifier cavity, and phase-locked stacking into one dominant pulse. An optimized regenerative amplifier design for non-overlapping pulse train amplification is presented.
We report on the design and performance of a cryogenic kilohertz Yb:CaF2 CPA producing 30-mJ, 200-fs pulses. A two-stage scheme enables bistability-free amplification in the repetition frequency range of 0.5–10 kHz, sustaining >20 W average power.
THz generation scalable to high energies in ZnTe and GaP by tilted pulse front pumping at 1.45 and 1.7 μm wavelength was demonstrated. Up to 0.7% efficiency and 14 μJ energy were achieved.
A novel ZnTe contact-grating THz source, pumped above the three-photon absorption edge, was demonstrated. THz pulses up to 3.9 μJ energy were generated with up to 0.3% efficiency, 100× higher than reported previously for ZnTe.
We report on 3.2 μm pulse post-compression via spectral broadening in hollow core capillary filled with noble gas. The mid-IR input pulses are generated in a femtosecond OPA based on KTA crystals, which delivers 6 mJ, 80 fs, 3.2 μm CEP-stable idler pulses. Pulses were spectrally broadened in a 3 meter long differentially pumped hollow-core capillary with ∼50% transmission and a statically filled 50...
THz pulses up to 14 J energy and 0.7% efficiency were generated by ZnTe sources with tilted pulse front pumping at 1.7 μm, above the three-photon absorption edge. A monolithic ZnTe contact-grating source was demonstrated, which is scalable to mJ energies.
We report on the generation of high-energy few-optical-cycle pulses in mid-infrared spectral region via self-compression in transparent dielectrics and filaments as well as via four wave parametric amplification in gas-filled hollow waveguides.
We report on the design and performance of a Yb:CaF2 booster with a pass-by-pass compensated spatial gain narrowing. A 5-concave-mirror design affords a flexible number of passes as well as 4f image relay and progressive beam magnification onto the laser crystal.
We present experimental and numerical progress in the development of nonlinear directional couplers based on multicomponent glass photonic crystal fibre. The first part of the paper reports a multi-wavelength nonlinear switch, operating in ultralong wavelength optical communication band, based on a special square lattice dual-core photonic crystal fibre excited with femtosecond pulses. The soliton-fission...
Optical parametric chirped pulse amplification (OPCPA) is rapidly gaining ground as an approach to generate intense few-cycle pulses and reach IR wavelength ranges [1]. However, the high OPA gain has its negative side: for a bell-shaped intensity profile of the pump pulse/beam the unsaturated gain varies exponentially with intensity, resulting in an effective temporal/spatial filter. Here we demonstrate...
The gain bandwidth of Ho-doped crystals is sufficiently broad to support femtosecond operation, which would allow pumping of ultrashort-pulse mid-IR optical parametric amplifiers (OPAs) [1,2] and, upon reaching adequate peak powers, eye-safe filamentation in the >2-μm transparency window of the atmosphere. In this contribution, we report on, to our knowledge, the first demonstration of a femtosecond...
Femtosecond Tm-fiber-laser-pumped Ho:YAG room-temperature CPA system delivering scalable multi-mJ multi-kHz pulses with a bandwidth exceeding 12 nm and the average power of 15 W is developed. Recompressed 530-fs pulses are suitable for broadband WL generation in transparent solids.
We report on high single-pass gain in Yb:CaF2 crystal longitudinally pumped with a 40 W high-brightness fiber laser source based on an ytterbium-doped ultra-large core photonic crystal rod-type fiber operating at 976 nm. A single-pass small-signal gain of 3.2 has been achieved in a 6 % Yb-doped 10-mm-long CaF2 crystal at room temperature, outperforming any CW-diode-pumped scheme and paving the way...
Using a 3.9µm driving laser focused into a high-pressure gas-filled waveguide, we generate bright, phase matched, fully spatially coherent high harmonic beams in the keV region for the first time.
We report on experimental results in adaptive control over UV fluorescence from a femtosecond filament created in nitrogen. We demonstrate that an optimized sequence of femtosecond pulses can effectively align, selectively ionize and excite molecular nitrogen ions, resulting in stimulated amplification of a filament continuum seeded emission at 391 nm, 358 nm and 428 nm wavelengths.
Using a 3.9μm driving laser focused into a high-pressure gas-filled waveguide, we generate bright, phase matched, fully spatially coherent high harmonic beams in the keV region for the first time.
Energy saturation is achieved by seeding 1-kHz Yb:CaF2 amplifier by μJ pulses from a monolithic Yb-fiber MOPA leading to 6-mJ output. The saturation is possible at any rep-rate with appropriate seed and optical loss levels.
We present a unified picture of phase matching of high harmonic upconversion spanning the electromagnetic spectrum from the VUV to keV, combining both microscopic and macroscopic physics. We validate this picture with experiment and theory.
We realize a multicolor, multi-cycle combination of commonly CEP-locked three waves from a single femtosecond OPA driven by a CEP-stable 7-mJ kHz Yb laser system and report HHG driving with individual and combined colors.
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