SBIR-STTR Award

The proposed work will investigate unique multilayer coating design architectures utilizing 2-Dimensional (2D) layered materials with giant two-photon absorption, such as WS2 and WSe2, placed between multilayer Bragg mirrors to produce reflective optical limiters. These optical limiters will transition from transparent to reflective when the incoming intensity exceeds a critical value. This represents a unique approach to manipulation high energy coherent beams, as most approaches rely on a transition to a high absorption level to protect underlying materials or components which typically results in significant damage of the absorber, and therefore limited durability. In addition, our approach offers significant improvements to the dynamic range and enables a tailored broadband response, while the transmission frequencies can be tailored to act as a filter at low irradiance levels, thereby providing increased functionality. If successful, this technology can help mitigate threats from high energy coherent beams of multiple wavelengths in a single system, with high durability, representing a unique asymmetric advantage over potential adversaries or threats. In addition, this technology has uses throughout the optics and electronics fields for transmission and redirection of coherent beams.

To maximize our military effectiveness, the US must maintain an asymmetric advantage with its next generation technology and weapons. Directed energy weapons such as lasers are one class of weapons in which the US can maintain this advantage by also developing advanced laser defense technology. This proposal builds on our Phase I results using reflective optical limiter coatings which mitigate laser damage and exhibit a high damage tolerance. These coatings are non-sacrificial as they do not absorb the light like most optical limiters and are also multifunctional as they enable transmission of low intensity wavelengths within the reflective band. The proposed Phase II work will investigate process optimization to yield optical limiters which will be tailored to function against common laser wavelengths across the Vis, NIR, and mid IR. In addition, the work will seek to develop broadband reflectors which can protect against numerous wavelengths within a single coating. Finally, a combined modeling and experimental approach will be utilized to investigate the capability of enabling low intensity transmission for multiple wavelengths and embedded transmission in the broadband reflectors. The coatings will be deposited utilizing combinations of PVD and CVD techniques and evaluated using state of the art characterization facilities.