# The Electromagnetic Shielding of Optoelectronic Devices by Mesh Structures
## 4 Results and Discussion
The transmission of the mesh structure in a frequency range of 0.1-3 THz for sample 1 and sample 2 is shown in Figure 5. The transmission of the free-standing mesh structure is shown in Figure 5 by the red line, and the transmission of the mesh structure on the OHARA S-BSL7/Schott N-BK7 glass is shown by the blue line. Both glasses are analogs of the K108 glass, which was used in the experiment. For the evaluation of the limit of applicability of the one-mode calculation [13], a comparison of this model with the numerical calculation of free-standing mesh structure transmission was carried out. The one-mode calculation of the transmission coefficient is shown in Figure 5 by the black line. The analytical model of the transmission coefficient fits sufficiently well with the numerical calculation up to a resonant peak. After the resonant peak, the transmission coefficient is lower than that calculated using the numerical calculation and the resonant peaks associated with the high order modes are absent. The experimental transmission of the mesh structures in a wide spectral range of 0.185-3000 \(\upmu\)m is shown in Figure 6. The bandwidth of this mesh structures is clearly visible in the spectrum. A comparison of transmission spectra of the free-standing mesh structure, the mesh structure on the substrate, and the pure substrate shows that the transmission of the glass can be superimposed on the free-standing mesh structure transmission. Therefore, the transmission of the mesh structure on the substrate becomes a band pass with two transmission bands: in the spectral ranges from visible to near-IR and in the THz frequency range. Since the operating spectral range of OEDs such as video cameras and laser rangefinders are located in the visible and near-IR ranges, it is necessary to maximize the transmission in this spectral range. For a solution to this problem, an AR coating was used. The samples  
Figure 6: Experimental transmission spectra of mesh structures on K108 glass. The blue, red, and black curves denote sample 1, sample 2, and K108 glass, respectively. were fabricated with alternating zirconium and silicon dioxide layers with a total thickness of 420 nm for the 1.55 \(\upmu\)m wavelength (for the laser rangefinder) and of 395 \(\upmu\)m for the 0.515 \(\upmu\)m wavelength (for the video camera), respectively. The experimental transmission spectra of the mesh structure on the glass with and without the AR coating are shown in Figure 7. Due to the AR coating, the transmission coefficient was increased in the wavelength range from 0.35 \(\upmu\)m to 2 \(\upmu\)m.  
Though the shielding properties of these mesh structures are inferior to some types of shielding structures, they also have a number of advantages. Although a filter based on carbon nanotubes has higher attenuation in the operating frequency range than the mesh structure it cannot be used as a band pass filter in the visible and near-IR wavelength ranges [7]. Filters with non-traditional surface designs (e.g., with contiguous rings [10] or petal-shaped [11]) have good shielding abilities. A disadvantage of such filters is the complexity of the formation of these structures. A comparison of the shielding properties of the mesh structures with other shielding structures is shown in Table 1. At a frequency of 12 GHz, the attenuations in the mesh structures with the sizes 90 \(\upmu\)m \(\times\) 10 \(\upmu\)m \(\times\) 5 \(\upmu\)m and 280 \(\upmu\)m \(\times\) 20 \(\upmu\)m \(\times\) 5 \(\upmu\)m is 34 dB and 23 dB, respectively, which are better or comparable with the filter based on the carbon nanotubes layer (25 dB for 10 nm thickness) [7], the mesh  
Figure 7: Transmission spectra of mesh structures with AR coating at 1.55 \(\upmu\)m (**a**) and in the visible range (**b**) as well as without AR coating. structure made of contiguous rings (20 dB) [10], and the petal-shaped mesh structure (31 dB) [11].