  With the increasing complexity of the electromagnetic environment,
electromagnetic interference has already been an important problem for
optoelectronic systems to be reckoned with. The metal mesh film is a kind of
widely used electromagnetic shielding material with both visible and infrared
transparency. However, the shielding performance of previously reported mesh
materials is frequency dependent. Here, we report an infrared-transparent
electromagnetic shielding windows based on metal mesh with irregular patterns.
The mesh coatings are prepared on sapphire substrate using ultraviolet
photolithography technology, and provide efficient electromagnetic shielding
effectiveness of more than 20 dB in the wide frequency range of 1.7~18 GHz
while maintaining high infrared optical transparency. In addition, there is no
distinct variation in shielding effectiveness between low and high frequency
range, exhibiting a balanced shielding characteristic throughout a broad
frequency band. This work could be significant in protecting infrared
optoelectronic devices from electromagnetic interference.
