But why are researchers interested in building such a powerful diode array?
LLNL engineers are currently in the process of building a much larger machine, the High-Repetition-Rate Advanced Petawatt Laser System (HAPLS), which will generate peak powers that exceed one petawatt (1015 watts). But before engineers can flip the switch on HAPLS they’ll have to assemble a number of these diode arrays to meet the power requirements expected from the HAPLS system.
In the past, high-powered lasers have used white-light flashlamps to “pump” atoms within a piece of laser glass into a more excited energetic state. The problem with flashlamps, however, is that they generate a tremendous amount of heat when they go off. Even though a flash lamp only flickers for a fraction of a second, the heat they produce limits the amount of energy they can pump into a lazing medium. Because of this heat flashlamps can only be fired once every second, limiting the number of atoms that can be excited and dulling the laser’s energetic concentration.
For high-energy laser research that’s a non-starter.
“Flashlamp technology for lasers has been around for more than 50 years, and we’ve pretty much pushed the limits of that technology and maxed out what we can do with them,” said Andy Bayramian, systems architect on HAPLS. “We’ve closed the books on flashlamps and started a new one with these laser diode arrays, enabling a far more advanced class of high-energy laser systems.”
Extreme temperature fluctuations are no longer an issue with laser diode arrays. In fact, since the LLNL diode array can keep itself cool it can fire pulses of light into a medium around 10 times per second, a significant improvement over its flashlamp predecessor.
In the end, the entire HAPLS system will be shipped off to the Czech Republic where it will be installed in the European Union’s Extreme Light Infrastructure Beamlines facility. Once installed, the HAPLS system is expected to help advance the state of the art in a number of fields, including advanced imaging, particle acceleration, biophysics, chemistry and quantum physics.
Aside from fundamental research, engineers also expect that HAPLS will have implications in the national security arena and the world of industrial processes. Researchers also suspect that HAPLS might pave the way to a new era of laser peening (a method for making turbine blades less susceptible to foreign object damage) and laser fusion.
Source: Lawrence Livermore National Lab