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Electro-optic modulator with MgO strips and gold (Au) electrodes. (a) General view of the modulator structure; (b) Cross-section view of the modulator structure; (c) The cross-distribution of the TM fundamental mode, electric field.
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The performance improvement of rib-waveguide electro-optic (EO) polymer modulators resulting from the inclusion of high permittivity dielectric strips is considered. For this study, we take into account the heterogeneous nature of the poling of the electro-optic polymer by the electrode structure, the dispersion of the RF wave due to the material d...
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... parameters, and improvements in the fabrication tech- nology [1,6,13]. For correct design and numerical modeling of EO elements it is important to consider all the pertinent factors influencing the modulator operation. The present work is focused on advanced modeling and improving the design of rib-type polymer electro-optic modulators (see Fig. ...
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... influence of the frequency dependence of dielectric permittivity on modulator characteristics is not considered. Nevertheless, Li et al. [2] discuss this effect in due measure. We consider their approach (which takes into account a material dispersion) to be the most appropriate for the task at hand, and it is therefore used in the present work. Fig. 1. In a number of publications, it is noted that experimental rib-type EO polymer modulators have in-device effective electrooptic coefficient considerably smaller (by 30%-50%) than those measured in homogeneously poled single films [17,18]. One of the reasons for this disparity is that the polling of the polymer layers in the fabricated ...
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... have focused our research on electro-optic modulators that are simplest to fabricate; those based on the inverted rib-type optical waveguides (see Fig. 1) with push-pull poling and a large mode cross section which enables operation at high transmitted optical powers ...
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... general structure of the electro-optic modulator and its main features are schematically presented in a Fig. 1. Properties of the RF wave in the modulator are mainly defined by average dielectric permittivity in the space region surrounding the electrodes and by the total thickness, H tot , of the polymer layer, as well as the conductivity, thickness, and width of signal ...
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... fundamental optical mode (see Fig. 1c) extends outside the rib waveguide for a distance of several microns. Therefore, the separation distance (Sep) between the centers of the rib waveguides in the modulator region should be large enough to reduce parasitic effects due to coupling between the guided optical modes of two rib waveguides, while remaining smaller than the ...
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... thick low index buffer from the waveguide core in such a manner that their optical properties do not significantly influence the guided mode propagation; they contribute a total additional loss of less than 0.1 dB/cm. These considerations are included in the calculation and in the optimization of the polymer electro-optic modulator presented in Fig. 1. Fig. 2 Currently magnesium oxide (MgO) is used as the preferred protective layer for plasma display panels (PDPs) owing to its combined properties of excellent resistance to sputtering and high secondary electron emissions [20]. On the other hand, recent studies have revealed that MgO is interesting as a high-k gate dielectric [21]. ...
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... the first stage, we calculated the potential and electric field distributions (see Fig. 3) in the structure which are presented in Fig. 1. The polymer layers with low conductivity values ( 1 = 3 = 10 −9 S/m and 2 = 10 −10 S/m) [25] have been replaced, for our simulation purposes, by the "effective dielectric constants" ε 1,3 = ε 0 · 1,3 = 113 and ε 2 = ε 0 · 2 = 11.3, respectively, and the dielectric MgO insertions, corresponded to zero conductivity, have been replaced ...
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... the design structure presented in Fig. 1, the maximum electro-optic efficiency corresponds to the propagation of an optical wave with TМ polarization in the polymer waveguides. To define the refraction-index change n due to a RF modulation, we calculate the inhomogeneous distribution an electro-optic constant which is proportional to the vertical component of the electric ...
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... necessary coupling coefficient for minimum transmitted signal T 11 at zero voltage of these couplers is obtained by choosing the optimal gap W g between coupled waveguides (see Fig. 7a). A similar result could be obtained by applying voltages to additional electrodes arranged around the splitter (see Electrode 1 and Electrode 3 in Fig. 1a) to provide the necessary splitting ratio (see Fig. 7b). Note that these electrodes can also be used for compensation of possible device parameter variation due to manufacturing ...
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... comparison we present in Fig. 8 the results of competitive simulations of two variants of EO polymer modulators. shows the dependence of transmitted power, T 11 , from input (In1) to output (Out1) of the Mach-Zehnder interferometer (see Fig. 1a) for different frequencies up to 100 GHz. The presence of MgO strips fulfills two functions: (i) it decreases the velocity mismatch between the RF and optical waves, and (ii) it optimizes the voltage cross-section spatial distribution to enhance the poling effect in the rib ...
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... case, "MgO", corresponds to the structure in Fig. 1b with an additional underlayer of MgO. The case, "UV15LV", corresponds to the structure in Fig. 1b without MgO, where all "MgO" space is uniformly filled by polymer, UV15LV. Both structures have optimized parameters to provide better performance. It can be seen that the waveguides with MgO have improved efficiencies of electrooptic ...
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... case, "MgO", corresponds to the structure in Fig. 1b with an additional underlayer of MgO. The case, "UV15LV", corresponds to the structure in Fig. 1b without MgO, where all "MgO" space is uniformly filled by polymer, UV15LV. Both structures have optimized parameters to provide better performance. It can be seen that the waveguides with MgO have improved efficiencies of electrooptic control (1.2-2.8 times). This improves further with increasing frequency and electrode ...
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Citations
... For long haul networks, dense photonic integration may be favorable for reducing cost over current switching technologies by taking advantage of large-scale integration utilizing silicon-based manufacturing [15]. Unfortunately, the EO effect in silicon is relatively low and therefore a polymer with high EO coefficient may be embedded in the MZ configuration arms to reduce the required applied voltage (i.e., reduces the V π L parameter) [16,17]. ...
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... Similar anomalously high values of the EO response, whose cause was not definitely established, were reported in [11]. The great influence of the electrophysical parameters of the layers on the electric-field distribution in the structure was shown in [12]. In our opinion, the cause of the low half-wave voltage is related to the ratio of the conductivities of the materials used. ...
This paper describes the development and investigation of compact waveguide electrooptic modulators using original synthesized chromophore-containing polyimides with covalently attached commercial DR-13 dye. Fully polymer planar electro-optic structures with phase-polarization and amplitude modulators in the form of a Mach–Zehnder interferometer were developed and implemented. The characteristics of the developed modulators at a wavelength of 1.3 μm were investigated, and a half-wave voltage of 24 V was achieved with a 1.3 cm length of the active part of the modulator.
The optical switch is one of the vital constituents of today's fiber‐optic communication system. Among diverse optical switches, the electro‐optical switch has the potential to project itself ahead of others owing to its unique structure and novel characteristics. However, to maximize the potential of the electro‐optical switch, the basic operating principle needs to be grasped along with the optimization of the suitable materials for fabrication. Finally, an easy route of fabrication has to be devised and the characteristics of synthesized switches need to be studied. This chapter will summarize the basic operating principles of electro‐optic switching together with suitable fabrication materials and the characteristics of synthesized switches.
Polymer-based electro-optic (EO) modulators have the advantages of low half-wave voltages and a low-cost preparation process and thus have extensive application prospects. A flexible, low half-wave voltage SU-8 Mach–Zehnder (M-Z) EO polymer modulator was proposed for human electrocardiogram (ECG) signal detection; polydimethylsiloxane (PDMS) was used as the substrate, and crosslinked polymer disperse red 1 (DR1)/SU-8 was used as the waveguide core layer. PDMS surface modification and SU-8 polarization were achieved, and the device was prepared by spin coating, ultraviolet (UV) lithography, wet etching and low-temperature sputtering. The experimental results show that the modulator initially operates in a linear operating regime under unbiased voltage conditions, and direct linear modulation of the voltage can be realized. After the preparation process, the low half-wave voltage was measured to be 2 V with a core size of 4000 μm×22000 μm, and the loss of the device was −2.1 dB.
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