The use of lasers for directed energy military applications allow for target engagements at “light speed” that can damage or destroy a target almost instantly upon target acquisition. Increasing the power while reducing the size and weight, collectively known as SWaP, is essential for these lasers to be used on a wide variety of Army, Navy, Air Force, Marine or Coast Guard platforms. The key to SWaP optimization is a highly efficient, low weight, and small-scale laser diode pump. Size and performance are important, as kilowatt and megawatt-class directed energy lasers require thousands of laser diode pumps, otherwise known as the “laser in the “laser.”
A laser diode pump is comprised of three critical components: the laser diode, the power supply, and a fluid chiller that removes excess heat. When electrical energy is applied to the semiconductor laser diode, the device produces light that optically “pumps” the gain medium, which acts as a storage device. Power requirements range based on the intended application within the defense market.
Low-Power Laser Systems
Small, low-powered laser systems are required to engage compact UAVs with directed energy weapons. For this application, lasers in the 5-10 kW optical power range have been demonstrated in the field. The ideal deployment of these lower powered weapons would be a man-portable platform capable of being used in a forward operating base.
High-Power Laser Systems
DE lasers in the class of 100 kW to 1 MW are needed to pursue applications including anti-cruise and ballistic missiles. This increased power reduces the time the laser needs to be held on a target and allows for effective targeting at an increased range.
Optimizing the SWaP of a directed energy laser system is most easily achieved via the SWaP optimization of the pump diode. This concern makes a diode SWaP an essential optimization step in the design stage. There are three effective ways to optimize a laser diode pump for these requirements:
- Increase laser diode power per bar to require fewer stacks
- Improve the power efficiency to limit the number of chillers and power supplies needed
- Increase laser diode brightness through advanced packaging, such as closely packing laser diodes together and using additional optical components like micro-lenses and delivery fibers
Leonardo’s engineering team continues to focus on many of these areas of optimization. Some of the key laser diode pump capabilities we have recently developed include a 1cm laser diode capable of over 1kW peak output power (2X any other laser bar). Additionally, Leonardo is developing a fiber laser pump capable of over 650W of CW power out of a 225µm delivery fiber. Both products are engineered to utilize airborne-compatible fluid that does not freeze at sub-zero temperatures to assist in the cooling and limiting chillers. Packaging is something we discuss with every customer to achieve the exact operating parameters required. To learn more, contact us.
To learn more about directed energy requirements and designing technology for directed energy, download the full white paper.
