Surface Plasmon Polariton Based Polarization Modulators Using Metal-polymer Waveguides

A tunable polarization modulator based on the periodic metal strips embedded in a polymer waveguide is presented. The periodic metallic structure is analyzed by Finite Element simulation (COMSOL). The calculation results show that the giant birefringence is formed by the selective cut-off of TE polarization over TM polarization, which makes it possible to design an efficient polarization modulator with a short conversion length. The metallic strips are made by using four-layer lift-off fabrication technology. The transmission and group indices of TE and TM modes are measured. However, it is observed that TE and TM modes cut off at same time, which does not agree with our predictions. The reason for failure is that the change in refractive indices is different from what we expected, which makes the device perform in opposite way. Finally, further suggestions are provided to modify the design so that the device can achieve its expected function.MAS