Horizontally slotted electro-optic silicon waveguides featuring an organic crystalline slot material

The authors demonstrate EO modulation in horizontally slotted silicon/organic hybrid devices with crystalline organic BNA (N-benzyl-2-methyl-4-nitroaniline) as the EO active material in the slot. BNA crystals were grown from the melt in horizontal slots that were obtained from fusion bonding correspondingly structured SOI wafers. Devices were prepared from phosphorous implanted SOI wafers (220 nm thick SOI layer) with thermal oxide grown on the device silicon layer. The slot structures were patterned with conventional optical photolithography and wet etching into the thermally grown oxide, thereby producing a slot width of about 1000 nm and a height corresponding to the thermal oxide thickness of about 160 nm. A second device silicon layer was fusion bonded on top of the patterned substrate wafer. A scanning electron microscope image of a typical slot cross-section in the horizontally slotted waveguides is shown.