Poly-Crystalline Silicon Waveguide Devices on Hollow Deep Trench Isolation in Standard Foundry Bulk Silicon Process

We demonstrate poly-crystalline silicon waveguide devices on deep-trench isolation in a commercial bulk 180nm SiGe BiCMOS process without any process modifications or post-processing. At 1550 nm, the measured loss for the poly-crystalline silicon waveguide and an MMI compatible with the waveguide are around 3.0 dB/mm and 0.38 dB, respectively.