A vertical-junction carrier-injection micro-ring modulator fabricated in AIM Photonics’ quantum FLEX platform

We demonstrate a vertical-junction, carrier-injection, micro-ring modulator that is fabricated using AIM Photonics' 300 mm Quantum FLEX Platform which shows results with high modulation efficiency and a large ON-OFF ratio. The modulator device includes a ring and a single-bus, straight waveguide. The ring has a radius of 7 μm and a 220 nm silicon-on-insulator (SOI) waveguide is used both for the ring and the straight waveguides with a rib structure of 110-nm slab thickness. The width of the core waveguide is 550 nm for both the ring and the straight waveguides. The slab width between the full-height silicon core and contact area is kept at 1 μm on both sides from the 550-nm core. The coupling gap between the ring and the bus waveguide is designed to be 150 nm. To make the waveguide core vertical junction, the upper half of the core is n-doped and the lower half is p-doped. To have a smooth electrical connectivity between the core and the contact area, three-level doping is applied where the core is doped with the minimum concentration and the contact silicon area is doped with the highest concentration. The modulator is tested with a tunable laser over a 100-nm window extending from 1485 nm to 1585 nm. The light is coupled to the modulator using grating couplers which are used to couple input and output light. The vertical junction shows excellent direct current (DC) I-V characteristics and the modulator performs at high modulation efficiency of about 1.14 nm and a large ON-OFF ratio of about 21 dB at 1.0 V.