# The Electromagnetic Shielding of Optoelectronic Devices by Mesh Structures
## 3 Samples and Measurement Methods  
The samples were windows made of an optical K108 glass (TYDEX LLC, Saint Petersburg, Russia [15]). The K108 optical glass is an analog of the well-known K8 glass (BK7 by Short Company, Mainz, Germany). This means that these glasses (K108 and K8) have the same refractory index and absorption coefficients in the frequency range under study. The K108 optical glass is radiation-resistant, which can be useful in protecting OEDs under the influence of powerful microwave radiation. The thicknesses of the windows were the same and equal to 3 mm. Copper mesh structures with a square cell were sputtered on one side of each glass by MEMS (micro-electromechanical systems) technology. The size of the cell was chosen to obtain the optimal attenuation of the electromagnetic radiation. The cell size was modified to check the influence on the transmission coefficient in a wavelength range from visible to microwave: the size aperture was decreased by 3 times, the conductor width was decreased by 2 times, and its thickness remained unchanged. The mesh structure parameters (the square side \(\times\) the copper conductor width \(\times\) the conductor thickness) were 280 \(\upmu\)m \(\times\) 20 \(\upmu\)m \(\times\) 5 \(\upmu\)m (Figure 2a) and 90 \(\upmu\)m \(\times\) 10 \(\upmu\)m \(\times\) 5 \(\upmu\)m (Figure 2b). Since the operating spectral range of the mesh structures is in the range of visible/near-IR radiation, it is necessary to reduce the reflection of the structure in this spectral range. For this purpose, the reverse side of the window was covered with an AR coating. The coating was sputtered on the glass. It consisted of alternating layers of SiO\({}_{2}\) and ZrO\({}_{2}\) with  
Figure 1: The mesh structure type described by the one-mode calculation of a transmission coefficient: a square lattice (**a**,**c**) and a triangular equilateral lattice (**b**,**d**) with square (**a**,**b**) and circle apertures (**c**,**d**). refractive indices n(SiO\({}_{2}\)) = 1.45 and n(ZrO\({}_{2}\)) = 1.95, respectively. The layers were arranged in the following way (a layer thickness is indicated in parentheses): glass-SiO\({}_{2}\) (100 nm)-ZrO\({}_{2}\) (10 nm)-SiO\({}_{2}\) (55 nm)-ZrO\({}_{2}\) (48 nm)-SiO\({}_{2}\) (11 nm)-ZrO\({}_{2}\) (78 nm)-SiO\({}_{2}\) (98 nm)-air (seven layers in the AR coating). The function of these coatings is as follows: if the optical thickness of the AR coating equals a quarter of the incident radiation wavelength \(\lambda/4\), then destructive interference appears at the air/AR interface between a reflected and an incoming wave and increases the transmission coefficient [9]. The transmission spectrum was measured by the following equipment (Figure 3): a Photon RT spectrophotometer (EssentOptic LTD, Borovlyany, Republic of Belarus), a Bruker Vertex 70 Fourier-spectrometer (Bruker Corporation, Billerica, MA, USA), and a Tera K8 Menlo Systems THz time-domain spectrometer (Menlo Systems GmbH, Martinsried, Germany) used in spectral ranges from 185 nm to 1.65 \(\upmu\)m, from 0.9 \(\upmu\)m to 670 \(\upmu\)m, and from 150 \(\upmu\)m to 3 mm, respectively. The spectral resolutions of the Photon RT spectrophotometer were 0.3 nm, 0.6 nm, and 1.2 nm for the spectral ranges 185-350 nm, 350-990 nm, and 990-1650 nm, respectively. The spectral resolution of the Bruker Vertex 70 Fourier-spectrometer is 0.5 cm\({}^{-1}\). The frequency resolution of the Tera K8 Menlo Systems THz time-domain spectrometer is 1 GHz. All spectra obtained by the Photon RT, the Bruker Vertex 70, and the Tera K8 Menlo Systems spectrometers were merged into one spectrum by Bruker OPUS software (Bruker Corporation, Billerica, MA, USA) with a built-in Merge Spectra Ranges function, which averaged the spectra in the intersection wavelength range. The Bruker's OPUS has a set of built-in functions to measure and analyze the spectra including averaging and smoothing functions. A five-point smooth adjacent averaging function was applied to the full spectrum.