Noncollinear Enhancement Cavity for Record-High Out-Coupling Efficiency of an Extreme-UV Frequency Comb.

We demonstrate a femtosecond enhancement cavity with a crossed-beam geometry for efficient generation and extraction of extreme-ultraviolet (XUV) frequency combs at a 154 MHz repetition rate. We achieve a record-high out-coupled power of 600  μW, directly usable for spectroscopy, at a wavelength of 97 nm. This corresponds to a >60% out-coupling efficiency.

A nozzle for high-density supersonic gas jets at elevated temperatures.

We present the development of a gas nozzle providing high-density gas at elevated temperatures inside a vacuum environment. Fused silica is used as the nozzle material to allow the placement of the nozzle tip in close proximity to an intense, high-power laser beam, while minimizing the risk of sputtering nozzle tip material into the vacuum chamber. Elevating the gas temperature increases the gas-jet forward velocity, allowing us to replenish the gas volume in the laser-gas interaction region between consecutive laser shots.

Phase-stabilized 100 mW frequency comb near 10 μm.

Long-wavelength mid-infrared (MIR) frequency combs with high power and flexible tunability are highly desired for molecular spectroscopy, including investigation of large molecules such as C. We present a high power, phase-stabilized frequency comb near 10 μm, generated by a synchronously pumped, singly resonant optical parametric oscillator (OPO) based on AgGaSe. The OPO can be continuously tuned from 8.

Precise Access to the Molecular-Frame Complex Recombination Dipole through High-Harmonic Spectroscopy.

We report on spectral intensity and group delay measurements of the highest-occupied molecular-orbital (HOMO) recombination dipole moment of N_{2} in the molecular-frame using high harmonic spectroscopy. We take advantage of the long-wavelength 1.3  μm driving laser to isolate the HOMO in the near threshold region, 19-67 eV.

Size-dependent high-order harmonic generation in rare-gas clusters.

High-order harmonic generation (HHG) is investigated in rare-gas clusters as a function of the cluster size using 0.8 and 1.3  μm femtosecond lasers.