
Review of Recent Capability Improvements in Ultrashort Pulse Laser Sources: Closing the Relevancy Gap for Directed Energy Applications
A new generation of ultrashort pulse lasers (USPLs) have moved to new gain materials and new architectures that have realized not only an improvement in environmental tolerance, but also significant reductions in size, weight, and power consumption metrics.
Recent developments indicate the horizon for directed energy (DE) applications using ultrashort pulse lasers (USPLs) is quickly approaching.
Historically, USPLs were mainly confined to laboratory applications due to strict environmental requirements and complex operations requiring a high degree of operator education. These USPLs were based on solid-state technology involving titanium:sapphire (Ti:Sa) gain material, which is highly intolerant of temperature and humidity changes, vibrations, and atmospheric particulates. The new generation of USPLs have moved to new gain materials and new architectures that have realized not only an improvement in environmental tolerance but also significant reductions in size, weight, and power consumption (SWaP) metrics. This has led to new classes of USPLs that have achieved average powers (Pavg) and pulse repetition rates (fp) orders-of-magnitude higher than commercially available systems from as late as 2015.
USPLs operate over a wide range of wavelengths (λ), primarily in the infrared spectrum. The infrared is roughly broken down into the near (NIR, 0.7-1.4 μm), shortwave (SWIR, 1.4–3.0 μm), midwave (MWIR, 3.0–8.0 μm), longwave (LWIR, 8.0–15.0 μm), and far (FIR, 15.0–30.0 μm) ranges. For DE applications, we are often interested in propagating in air and thus limit our interests to particular wavelength ranges that minimize losses like absorption and scattering. These “atmospheric windows” are roughly in the visible and NIR (0.4–1.4 μm), the SWIR (2.0–2.5 μm), the MWIR (3.0–5.0 μm), and LWIR (8.0–14.0 μm) (see accompanying illustration).
In addition, the human retina is sensitive in the NIR and common silicon-based sensors are sensitive up to about 1.0 μm. An ideal USPL system for DE would emit at a wavelength in one of the atmospheric windows and be outside the sensitivity range of the retina and silicon sensor to minimize collateral effects.
There is a sizeable range of applications of USPLs and the specific requirements of laser systems can vary, limiting certain improvements that currently lack a business case. With the new generation of high average power USPLs being commercially available, new applications and new markets could develop in the next few years. “Table-top” sources of X-rays, electron beams, and proton beams could see widespread use as diagnostic tools for medicine, preventive maintenance, and materials science with improved SWaP metrics and reductions in cost. Yet all of these applications will one way or another make use of the special realm of physics, nonlinear optics, that USPLs are able to access.
This work was done by Anthony Valenzuela and Daniel Matyas for the Army Research Laboratory. For more information, download the Technical Support Package (free white paper) below. ARL-0241
This Brief includes a Technical Support Package (TSP).

Review of Recent Capability Improvements in Ultrashort Pulse Laser Sources: Closing the Relevancy Gap for Directed Energy Applications
(reference ARL-0241) is currently available for download from the TSP library.
Don't have an account? Sign up here.
Top Stories
INSIDERManned Systems
Army Launches M1E3 Tank Development, Cancels M1 Abrams Upgrade Program -...
INSIDERManned Systems
The B-21 Raider Starts Flight Testing - Mobility Engineering Technology
INSIDERDefense
Air Force Awards JetZero $235 Million to Develop Blended Wing Body Demonstrator...
INSIDERPower
Air Force Receives First eVTOL Six Months Ahead of Schedule - Mobility...
INSIDERDefense
Air Force to Buy Archer eVTOL Under New Contracts - Mobility Engineering...
ArticlesAerospace
Rim-Driven Electric Aircraft Propulsion - Mobility Engineering Technology
Webcasts
Research Lab
What Really Changed: A Look at the Updated FDA Guidance Document...
Power
Electrifying Off-Highway Drivetrains
Electronics & Computers
NVH Prediction in Electric Powertrains: Considering Inverter and...
Manufacturing & Prototyping
The Smaller the Part, the Bigger the Advantages of Miniature Aluminum Extrusions
Aerospace
Here's an Idea: How AI is Changing Military Aircraft Maintenance and More
Medical
Precision, Control and Repeatability: Harnessing the Power of UV Curing in...