Hybrid silicon-organic racetrack resonator designs for electro-optical modulation

摘要

Racetrack resonators based on the silicon-on-insulator platform are proposed for electro-optical modulation. The resonators are functionalized by a cladding of a second order nonlinear optical polymer. Two different concepts for the racetrack design employing different waveguide geometries for quasi-TE and quasi-TM polarization operation are presented. In both resonator designs the electrical contact is established by fully etched segmented electrode sections to allow for an easy fabrication process. For quasi-TM polarization the width of the strip waveguide is optimized to 400 nm. The Q factor of 2000 is measured for a sample with segmented electrode. A loss of 0.4 dB per segmented waveguide is deducted. For the quasi-TE polarization the slot waveguide geometry is optimized to 470 nm total width including a vertical slot of 90 nm width. Only the straight parts of the racetrack are slotted, while the bends are built from strip waveguides. To convert the mode from strip to slot geometry stub like couplers of 100 nm length are employed. The measured Q factor is 550. The in device Pockels coefficient is measured to r_(33) = 1 pm/V. This small value indicates a very low poling induced polar order which needs to be improved. This is a topic of current investigation.