Dual-function TE modulator and TM-pass polarizer using VO₂ phase changing material

The metal-insulator transition (MIT) of vanadium dioxide (VO 2 ) exhibits a great change in its complex refractive index. This is a key property for the design of ultra-compact photonic devices. In this paper, highly efficient TM pass polarizer and TE modulator are reported and numerically analyzed based on diffused waveguide with a double stack of VO 2 /PMMA layers. The idea here depends on achieving significant different mode profiles for orthogonal polarizations thanks to the MIT nature of VO 2 that can be extensively used in polarization-selective mode shaping. The two-dimensional finite element method (2D-FEM) is utilized to carry out the analysis of the reported device while finite difference time domain method (FDTD) is employed for investigating the light propagation through the proposed structure. The numerical results for a given device length of 50 μm at the telecommunication wavelength of 1.55 μm offers polarization extinction ratio (PER) of 20.8 dB and an insertion loss (IL) of about 0.089 dB for the TM pass polarizer during insulating phase. Changing to metallic phase, an extinction ratio (ER) as high as 20.4 dB and IL of 0.5 dB are achieved for the TE modulator. The presented polarizer/modulator has the advantages of large PER/ER, low IL and fabrication feasibility. Thus, it may be a good candidate for integrated photonics applications.