Efficient EMI/RFI attenuation by GaN-based coating on spinel windows

With the advent of electromagnetic and electro-optical sensors in modern military platforms, the issue of detectability extends well beyond that of visible light. The suppression of Electromagnetic Interference/Radio Frequency Interference (EMI/RFI) is considered as one of vital elements of survivability. In general, windows are one of the main sources of EMI/RFI signature. High optical quality windows transparent in 0.4-5µm range are required for shipboard electro-optical sensors. Magnesium aluminate spinel (MgAl2O4) due to the combination of mechanical and optical properties is the material of choice for these windows. At present, EMI/RFI shielding of windows is accomplished using metal grids or conductive transparent coatings which degrade their optical transmission properties. In this program, we propose to develop a robust, transparent coating for efficient EMI/RFI attenuation on spinel windows based on high-conductivity GaN thin films.