Background

In January of 2019, a list of 38 reports made under (or connected with) the Advanced Aerospace Threat Identification Program better known as AATIP, was released. It contained research into “invisibility cloaking” which sparked a huge amount of media and public interest. On January 31, 2019, George Knapp, investigative reporter with KLAS Las Vegas ran an interview with Harry Reid which made reference to the “invisibility cloaking” in the story.

I decided to scour my archive of FOIA documents, along with other military and government resources, and discovered quite a bit of research done outside of AATIP, on the topic of metamaterials and “invisibility cloaking.” Contracts and grants are connected with the U.S. Air Force Research Lab (AFRL), Army Research Office, Department of Defense (DOD), Defense Technical Information Center (DTIC) and the European Office of Aerospace R&D.

You will find a couple of the records below, are from symposiums that make reference to “invisibility cloak” technology as well.

Document Archive

OSA Incubators: Science and Applications of Nanolasers; and Subwavelength Photonics, July 2017 [36 Pages, 2.1MB] – Science and Applications of Nanolasers and Subwavelength Photonics Incubators were two separate meetings held in Washington, DC on 7-9 and 21-23 September 2016. The two Incubators provided unique and focused experiences and valuable opportunity to discuss advances, challenges and opportunities regarding the niche fields.

Constitutive Parameters of Metamaterial Structures Used for Invisible Cloak Realization, October 2013 [83 Pages, 4.3MB] – The realization of structures that do not scatter electromagnetic fields (“cloaking devices”) has been envisioned since the 1960s; recent advances in metamaterial research has shifted cloaking possibilities to this new field through transformation optics, creating a shell which effectively cloaks the space inside the shell by diverting EM radiation around it. The author finds such a cloak unfeasible in practice but investigates a simplified cloak design for one specific polarization of incident plane waves in an effort to improve the scattering properties of the realized cloaks. The proposed procedure attempts to characterize a planar structure, examine its realization using planar metamaterials, and then attempt to curve the metamaterials to obtain the desired geometry. The research proposes to develop this method, estimate parameters of planar multilayer periodic structures, and then estimate parameters of curved multilayer periodic structures. The main realized outcomes of the project are that the investigators proposed a four-step procedure to design metamaterial structures, investigated procedures to extract constitutive parameters of cloaks, showed design examples of structures containing different types of periodic-cell elements, and developed algorithms/programs for characterizing metamaterial structures including extensions of algorithms which calculate Green’s functions of anisotropic multilayer structures.

Metamaterials and Transformation Optics, July 2011 [9 Pages, 1.0MB] – Several US collaborations were reinforce during this period with several jointly authored papers appearing, mainly concerning the applications of metamaterials to cloaking. It is evident that there has been considerable exchange of ideas between the US groups and the Imperial College London group. This continues, and further exchange of personnel is planned for 2011.

9th Annual Science and Engineering Technology Conference/ DoD Technology Expo, 15-17 April 2008 [777 Pages, 42MB] – This is a large culmination of all of the power point presentations given at the aforementioned conference. The main title image (page 456) for this page comes from this powerpoint presentation, which has been converted to a pdf available here.