Design and Analysis of a Compact SOI-Based Aluminum/Highly Doped p-Type Silicon Hybrid Plasmonic Modulator

A silicon-based n-p-n-type hybrid plasmonic modulator operating at telecom wavelength of 1550 nm is theoretically investigated in this paper. The proposed modulator is dependent on the integration of a 1-μm-long n-p-n-type Al/p-Si hybrid plasmonic waveguide with Si waveguides. It is demonstrated that when the p-type silicon is highly doped, it shows metal-like properties which can support the propagation of surface plasmon polariton waves. The simulation results show that the output power of TE (TM) mode decreases from -7.6 dB (-2.5 dB) to -31.5 dB (-7.5 dB) when the Al stack is 0.2 μm high and the carrier concentration in p-Si is set to be 1 x 10
²¹
cm
^-3
, which is achieved with a voltage increase from 0 to 1.2 V. Such a plasmonic modulator not only depends on the propagation loss due to electroabsorption effect but takes advantage of the coupling loss raised by modal mismatch as well, which leads to a high modulation efficiency.