Commentary

Making Possible the Century of Photonics

For more than four decades, Lawrence Livermore has been at the forefront of laser technology. Our laser scientists and engineers push the limits of what is possible in their drive for ever-higher peak power and intensities, ultrashort pulses, and especially, average power. The Laboratory’s development of high-peak-power, short-pulse laser systems began in the mid-1980s, resulting in a 10-terawatt laser in 1989. Further efforts culminated in the kilojoule-class Nova Petawatt, achieving for the first time a peak power exceeding 10¹⁵ watts in 1996. Livermore’s development of high-peak-power, short-pulse laser systems continued in the 21st century with Falcon, Titan, and Callisto. Furthermore, the Advanced Radiographic Capability, currently under construction at the National Ignition Facility (NIF), will be the most energetic short-pulse laser in the world.

Now Livermore researchers have joined with European colleagues to build the High-Repetition-Rate Advanced Petawatt Laser System (HAPLS). As described in the article Lighting a New Era of Scientific Discovery, this instrument is designed to reach a peak power exceeding 1 petawatt at a repetition rate of 10 times per second to deliver intensities on target up to 10²³ watts per square centimeter. HAPLS is based on diode-pumped, solid-state laser technology, which ensures reliable delivery of this peak power at a high-repetition rate and at much-reduced electrical power consumption—a major advancement over current petawatt systems.

Following a worldwide assessment by the European laser community, Lawrence Livermore was chosen as the only organization qualified to build HAPLS. The laser system will be built and tested at the Laboratory to a predetermined set of project completion criteria and then delivered and commissioned at the Extreme Light Infrastructure (ELI) Beamlines facility, now under construction in the Czech Republic. HAPLS will be the highest average-power petawatt laser installed at the ELI Beamlines facility, which is the first in a series of advanced facilities comprising the ELI project. Scientists from the Czech Republic’s Institute of Physics are already working alongside Livermore physicists and engineers.

HAPLS embraces a host of groundbreaking technologies developed at Livermore. These technologies include helium-gas cooling of key components, advanced gratings that enable amplification of high-peak-power laser light without damaging optics, systems that constantly monitor themselves to minimize the need for human intervention, arrays of laser diodes that replace less efficient and bulky flashlamps, and advanced optics and optical finishing technologies.

The system’s pulses will be used to generate extremely bright and short x-ray pulses for imaging cells and proteins at unprecedented spatial and temporal resolution. Another application is generating bunches of protons or ions for medical therapy and materials science research. Scientists will also study the interaction of intense laser light with matter to improve prospects for laser fusion energy.

Our selection is a great honor and a testament to Livermore’s expertise in laser design, technology development, and record of successfully delivering projects that push the limits of existing technology. The award also is a testament to the confidence in our capabilities by the Board of Governors of Lawrence Livermore National Security, LLC. Because no precedent existed for this international partnership, the board agreed to underwrite any contract liabilities.

The Laboratory’s success in winning the HAPLS contract is due in large part to the long history of strategic investment in key capabilities through Livermore’s Laboratory Directed Research and Development (LDRD) Program and other internal funding mechanisms. The core competencies developed in optics, materials, and lasers through LDRD investments have resulted in the Laboratory’s unique capability to succeed on a project such as HAPLS. This project is proof that strategic investments can pay big dividends. The highlight Betatron X Rays Bring Focus to a Very Small, Very Fast World presents another example in which a modest investment has a high-payoff potential. A Livermore team is focusing ultrahigh-intensity light from Livermore’s Callisto laser on various gases to produce ultrashort x-ray pulses. This tabletop system produces the same x rays that typically require vastly larger particle accelerator and synchrotron facilities.

Building HAPLS with our European colleagues is surely one of the most exciting laser projects in the world and permits our researchers to continue to hone their craft. While the 20th century has been described as the Century of Electricity, this age may well prove to be the Century of Photonics. I expect to see lasers play an increasingly important role in our society, from medicine to industry to energy. I look forward to Lawrence Livermore contributing even more to this new era of light.