Designing and Optimization of Plasmonic Modulator Structure Based on the Active Materials of ITO and Graphene

In the last decade, optical integrated circuits, including modulators, have made significant progress in optical communications, imaging, and sensors. Among the active materials used in modulators, graphene and indium tin oxide (ITO) are some of the suitable options among the active materials for modulation action due to their epsilon-near-zero (ENZ) characteristics, speed, and considerable response. In this paper, by applying direct coupling of light, the structure of plasmonic modulator in three-dimensional mode has been designed. And by changing the thickness of ITO, HfO2 (hafnium oxide) layers and waveguide width, the structure is optimized. Optimization thickness of 3 nm for ITO, 5nm for HfO2 and 280nm for waveguide width is achieved. The results of three-dimensional simulations of this paper with appropriate coupling show that the insertion loss (IL) of three-dimensional mode have not changed and the extinction ratio (ER) of the modulator has been slightly reduced in comparison with two-dimensional mode .On the other hand, appropriate and optimal coupling has no effect on energy consumption.Three-dimensional results show that the proposed plasmonic modulator can achieve an extinction ratio of 13.9 dB, an insertion loss of 2.9 dB, modulation speed of 140.9 GHz and a very low power consumption of 1.51 fj/bit for a 1µm length of the modulator, at 0.5 V voltage and a wavelength of 1.55 µm. Our design demonstrates a considerable reduction in energy consumption and improvement in extinction ratio compared to previous works. Also, for a 2 µm length of the modulator, an extinction ratio of 27.76 dB, an insertion loss of 5.68 dB, modulation speed of 70.14 GHz and power consumption of 2.88 fj/bit is achieved.