Pulse compressor architecture to enable next-generation high-energy petawatt-class lasers.

The maximum energy obtainable within a single aperture of a high-energy petawatt-class (HEPW) laser is typically limited by the pulse compressor. This work evaluates the potential impact of two new pulse compression grating technologies (HELD gratings and TM polarization) on HEPW laser systems. A compressor architecture is proposed that implements these grating advancements in order to support ∼6× higher pulse energies than currently demonstrated.

Demonstration of a 1 TW peak power, joule-level ultrashort Tm:YLF laser.

We report on the demonstration of a diode-pumped, Tm:YLF-based, chirped pulse amplification laser system operating at λ ≈ 1.9 µm that produces amplified pulse energies exceeding 1.5 J using a single 8-pass power amplifier.

Office-Based Multilevel Radiofrequency Ablation for Mild-to-Moderate Obstructive Sleep Apnea.

Objective: Investigate multilevel radiofrequency ablation (RFA) as an alternative therapy for patients with mild-to-moderate obstructive sleep apnea (OSA).

Study Design: Prospective, open-label, single-arm, nonrandomized clinical trial.

Setting: Multicenter academic and private clinics.

Trapezius fasciocutaneous flap for burn reconstruction.

This case involves a 30-year-old female who suffered extensive facial burns as an outcome of a horrific assault. The patient subsequently underwent 2 surgeries with the ultimate goal of reducing the cosmetic, physical, and thus mental burden the assault caused. The technique of choice was the novel trapezius fasciocutaneous flap for burn reconstruction of the neck.

Femtosecond damage experiments and modeling of broadband mid-infrared dielectric diffraction gratings.

High peak and average power lasers with high wall-plug efficiency, like the Big Aperture Thulium (BAT) laser, have garnered tremendous attention in laser technology. To meet the requirements of the BAT laser, we have developed low-dispersion reflection multilayer dielectric (MLD) gratings suitable for compression of high-energy pulses for operations at 2 micron wavelength. We carried out 10000-on-1 damage tests to investigate the fluence damage thresholds of the designed MLD gratings and mirrors, which were found between 100-230 mJ/cm.

A Case of Melkersson-Rosenthal Syndrome Treated With 5-FU.

The rarity of Melkersson-Rosenthal syndrome, or orofacial granulomatosis, can present with persistent midface bogginess. The management for previous reported cases has included corticosteroid injections, antihistamines, and antibiotics. In the current reported case, the patient was treated with 5-fluorouracil and has been responding positively.

Spatio-temporal focal spot characterization and modeling of the NIF ARC kilojoule picosecond laser.

The advanced radiographic capability (ARC) laser system, part of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory, is a short-pulse laser capability integrated into the NIF. The ARC is designed to provide adjustable pulse lengths of ∼1-38 in four independent beamlets, each with energies up to 1 kJ (depending on pulse duration). A detailed model of the ARC lasers has been developed that predicts the time- and space-resolved focal spots on target for each shot.

Injection laser system for Advanced Radiographic Capability using chirped pulse amplification on the National Ignition Facility.

We report on the design, performance, and qualification of the injection laser system designed to deliver joule-level chirped pulse beamlets arranged in dual rectangular beam formats into two main laser amplifier beamlines of the National Ignition Facility. The system is designed to meet the requirements of the Advanced Radiographic Capability upgrade with features that deliver performance, adjustability, and long-term reliability.

Active cooling of pulse compression diffraction gratings for high energy, high average power ultrafast lasers.

Laser energy absorption and subsequent heat removal from diffraction gratings in chirped pulse compressors poses a significant challenge in high repetition rate, high peak power laser development. In order to understand the average power limitations, we have modeled the time-resolved thermo-mechanical properties of current and advanced diffraction gratings. We have also developed and demonstrated a technique of actively cooling Petawatt scale, gold compressor gratings to operate at 600W of average power - a 15x increase over the highest average power petawatt laser currently in operation.

Picosecond laser damage performance assessment of multilayer dielectric gratings in vacuum.

Precise assessment of the high fluence performance of pulse compressor gratings is necessary to determine the safe operational limits of short-pulse high energy lasers. We have measured the picosecond laser damage behavior of multilayer dielectric (MLD) diffraction gratings used in the compression of chirped pulses on the Advanced Radiographic Capability (ARC) kilojoule petawatt laser system at the Lawrence Livermore National Laboratory (LLNL). We present optical damage density measurements of MLD gratings using the raster scan method in order to estimate operational performance.

Extreme ultraviolet laser-based table-top aerial image metrology of lithographic masks.

We have realized the first demonstration of a table-top aerial imaging microscope capable of characterizing pattern and defect printability in extreme ultraviolet lithography masks. The microscope combines the output of a 13.2 nm wavelength, table-top, plasma-based, EUV laser with zone plate optics to mimic the imaging conditions of an EUV lithographic stepper.

Improved beam characteristics of solid-target soft x-ray laser amplifiers by injection seeding with high harmonic pulses.

Injection seeding of solid-target soft x-ray laser amplifiers with high harmonic pulses is shown to dramatically improve the far-field laser beam profile and reduce the beam divergence. Measurements and two-dimensional simulations for a 13.9 nm nickel-like Ag amplifier show that the amplified beam divergence depends strongly on the seed and can therefore be controlled by selecting the divergence of the seed.

Acoustic phonetics in a clinical setting: a case study of /r/-distortion therapy with surgical intervention.

Acoustic measures are used to document the speech of a 6-year-old child with persistent /r/-distortion through several treatment interventions. The child originally presented a complex of speech disorders and was treated by a speech-language pathologist using phonological process techniques. The procedures successfully corrected most of his speech problems, although /r/ remained severely distorted.