Hybrid Plasmonic–Photonic–Organic Modulators With Low Insertion Loss and High Modulation Depth

Abstract

In this article, a novel hybrid plasmonic–photonic–organic electro-optical modulator based on Pockels effect is designed and numerically investigated by employing finite difference time domain and finite element methods at a wavelength of $\lambda \,= \,{\text{1.55}}\,\mu {\text{m}}$ . The presented modulator exhibits unique features such as the half-wave voltage–length product of 0.08 V⋅mm being in the range of modern plasmonic modulators. However, the design presented in this article represents a very low insertion loss of less than 2 dB in the wavelength range of 1.45–1.65 μ m. Moreover, the modulator has an energy consumption of approximately 25 fJ/Bit, modulation depth of approximately 35% and 80% at applied voltages of 5 and 10 V, and electro-optical bandwidth of more than 70 GHz. As the key component of the modulator, a novel hybrid plasmonic slot waveguide is introduced, which combines tight light confinement of plasmonic waveguides with the low loss feature of photonic waveguides. In particular, the presented waveguide enables tight light confinement and guiding in slots as narrow as 40 nm with remarkably low loss of less than 0.2 dB/ μ m, which makes them attractive for other applications in addition to the designed modulator. In this paper, the presented waveguides are thoroughly investigated and compared with plasmonic slot waveguides in terms of loss and modal characteristics.