By Josh Perry, Editor
[email protected]

Researchers at the University of Southern California (USC) Viterbi School of Engineering in Los Angeles, Calif. are working on next-generation infrared technologies that would enable autonomous vehicles to see through the elements, such as rain and fog, and discovered a new material that could enhance thermal imaging products.

Professor Jayakanth Ravichandran and Ph.D. student Shanyuan Niu in the lab where they develop next generation technologies. (Valentina Suarez and Jayakanth Ravichandran)

According to a report from USC, the researchers created a composition of barium, titanium, and sulfur (BaTiS₃) that filters incoming radiation to enhance thermal imaging systems.

“Thermal imaging systems can recognize changes in an object’s temperature by tracking the amount of radiation emitted from that object,” the report explained. “By following the temperature changes of particular objects, thermal imaging systems can identify movement even in the absence of visibility – a crucial function for self-driving cars.”

The next step for researchers is to build a working prototype using the new material to demonstrate its effectiveness and to find other materials that could enhance the functionality of thermal imaging systems even further.

The initial research was recently published in Nature Photonics. The abstract stated:

Optical anisotropy is a fundamental building block for linear and nonlinear optical components such as polarizers, wave plates, and phase-matching elements. In solid homogeneous materials, the strongest optical anisotropy is found in crystals such as calcite and rutile. Attempts to enhance anisotropic light–matter interaction often rely on artificial anisotropic micro/nanostructures (form birefringence).

“Here, we demonstrate rationally designed, giant optical anisotropy in single crystals of barium titanium sulfide (BaTiS₃). This material shows an unprecedented, broadband birefringence of up to 0.76 in the mid- to long-wave infrared, as well as a large dichroism window with absorption edges at 1.6 μm and 4.5 μm for light with polarization along two crystallographic axes on an easily accessible cleavage plane.

“The unusually large anisotropy is a result of the quasi-one-dimensional structure, combined with rational selection of the constituent ions to maximize the polarizability difference along different axes.”