A compact ring modulator with very large extinction ratio and high quality factor fabricated in AIM photonics technology at Albany Nanotech Complex

In this work, we demonstrate a compact pn junction ring modulator with very large extinction ratio and high quality factor. The modulator consists of a 5-μm radius ring and a single-bus straight waveguide. Both the ring and straight waveguides have a width of 480 nm and heigh of 220 nm. The waveguides are rib-structured and the rib thickness is 110 nm with a slab thickness of 110 nm from a 300mm wafer with 220-nm silicon-on-insulator (SOI) thickness. A 100-nm gap is designed between the rib ring and the bus waveguides. The modulator has three nominal doping levels with concentrations of 10¹⁸, 10¹⁹, and 10²⁰ cm^-3 for the core, slab, and the contact areas, respectively. The device is fabricated using the American Institute for Manufacturing integrated Photonics (AIM Photonics) Multi-Project Wafer (MPW) service. It is tested using the AIM Photonics inline vertical gratting coupled automated tool with a tunable light source that has wavelengths ranging from 1485 nm to 1590 nm and a wavelength resolution of 60 pm. The fabricated 5-μm radius ring modulator exhibits high quality output with a very large extinction ratio of 29 dB over a broad wavelength spectrum of about 100 nm. The device has a very wide free spectral range (FSR) of about 19 nm.