Krishna Murari

Compact x-ray source based on burst-mode inverse Compton scattering at 100 kHz

A design for a compact x-ray light source (CXLS) with flux and brilliance orders of magnitude beyond existing laboratory scale sources is presented. The source is based on inverse Compton scattering of a high brightness electron bunch on a picosecond laser pulse. The accelerator is a novel high-efficiency standing-wave linac and rf photoinjector powered by a single ultrastable rf transmitter at X-band rf frequency. The high efficiency permits operation at repetition rates up to 1 kHz, which is further boosted to 100 kHz by operating with trains of 100 bunches of 100 pC charge, each separated by 5 ns. The entire accelerator is approximately 1 meter long and produces hard x rays tunable over a wide range of photon energies. The colliding laser is a

Overcoming bifurcation instability in high-repetition-rate Ho:YLF regenerative amplifiers

\mathrm{Yb}\ensuremath{\mathbin:}\mathrm{YAG}

Intracavity gain shaping in millijoule-level, high gain Ho:YLF regenerative amplifiers

solid-state amplifier producing 1030 nm, 100 mJ pulses at the same 1 kHz repetition rate as the accelerator. The laser pulse is frequency-doubled and stored for many passes in a ringdown cavity to match the linac pulse structure. At a photon energy of 12.4 keV, the predicted x-ray flux is

Kagome-fiber-based pulse compression of mid-infrared picosecond pulses from a Ho:YLF amplifier

5\ifmmode\times\else\texttimes\fi{}1{0}^{11}\text{ }\text{ }\mathrm{photons}/\mathrm{second}

Numerical study of spectral shaping in high energy Ho:YLF amplifiers

in a 5% bandwidth and the brilliance is

Kagome-fiber-based pulse compression of mid-infrared picosecond pulses from a Ho:YLF amplifier: publisher’s note

2\ifmmode\times\else\texttimes\fi{}1{0}^{12}\text{ }\text{ }\mathrm{photons}/(\mathrm{sec}\text{ }{\mathrm{mm}}^{2}\text{ }{\mathrm{mrad}}^{2}\text{ }\text{ }0.1%)

High energy and low noise Ho:YLF regenerative amplifiers: A noise and stability analysis

in pulses with rms pulse length of 490 fs. The nominal electron beam parameters are 18 MeV kinetic energy, 10 microamp average current, 0.5 microsecond macropulse length, resulting in average electron beam power of 180 W. Optimization of the x-ray output is presented along with design of the accelerator, laser, and x-ray optic components that are specific to the particular characteristics of the Compton scattered x-ray pulses.

Direct Observation of Folding Energy Landscape of RNA Hairpin at Mechanical Loading Rates

We demonstrate a Ho:YLF regenerative amplifier (RA) overcoming bifurcation instability and consequently achieving high extraction energies of 6.9 mJ at a repetition rate of 1 kHz with pulse-to-pulse fluctuations of 1.1%. Measurements of the output pulse energy, corroborated by numerical simulations, identify an operation point (OP) that allows high-energy pulse extraction at a minimum noise level. Complete suppression of the onset of bifurcation was achieved by gain saturation after each pumping cycle in the Ho:YLF crystal via lowering the repetition rate and cooling the crystal. Even for moderate cooling, a significant temperature dependence of the Ho:YLF RA performance was observed.

Stability optimized, 4-mJ and 1.2-ps pulses from a Ho:YLF regenerative amplifier

We demonstrate intracavity gain shaping inside a 2 μm Ho:YLF regenerative amplifier with a spectral bandwidth of 2.9 nm broadened to 5.4 nm, corresponding to Fourier-limited pulses of 1 ps duration. The intracavity gain shaping is achieved by using a simple etalon, which acts as a frequency-selective filter. The output of the regenerative amplifier is amplified by a single-pass amplifier, and we achieve total energy of 2.2 mJ and pulse duration of 2.4 ps at 1 kHz with pulse fluctuations <1%. The amplifier chain is seeded by a home-built mode-locked holmium-doped fiber oscillator.

Strong-Field Few-Cycle 2-μm pulses via Kagome-Fiber Compression of Picosecond Ho:YLF Laser Pulses

Over the last decade, the development of ultrafast laser pulses in the mid-infrared (MIR) region has led to important breakthroughs in attosecond science and strong-field physics. However, as most such broadband MIR laser sources are near-IR pumped, the generation of high-intensity, long-wavelength MIR pulses is still a challenge, especially starting from picosecond pulses. Here we report, both experimentally and numerically, nonlinear pulse compression of sub-millijoule picosecond pulses down to sub-300 fs at 2050 nm wavelength in gas-filled Kagome-type hollow-core photonic crystal fibers for driving MIR optical parametric amplifiers. The pump laser is comprised of a compact fiber laser-seeded 2 μm chirped pulse amplification system based on a Ho:YLF crystal at 1 kHz repetition rate. Spectral broadening is studied for different experimental conditions with variations of gas pressure and incident pulse energies. The spectrally broadened 1.8 ps pulses with a Fourier-limited duration of 250 fs are compressed using an external prism-based compressor down to 285 fs and output energy of 125 μJ.