Direct-modulated waveguide-coupled microspiral disk lasers with spatially selective injection for on-chip optical interconnects

We investigate direct-modulated waveguide-coupled microspiral disk lasers for on-chip optical interconnects. Microspiral resonators, with a rotationally asymmetric shape and a waveguide directly gapless coupled to the notch, offer a compact unidirectional-emission on-chip laser source. We employ spatially selective injection by means of a ring-shaped p-contact on top of the microdisk rim region to selectively inject current to the whispering-gallery-like modes and thus enhance the laser performance. Here we report room-temperature continuous-wave electrically injected AlGaInAs/InP waveguide-coupled microspiral disk lasers with a disk radius of 30 and 40 μm. For a 30 μm microspiral disk laser gaplessly coupled with a 100 μm-long passive waveguide that is directly connected to an on-chip AlGaInAs/InP photodiode, we estimate a laser output power of at least 200 μW upon a 70 mA injection. We realize small-signal modulation with a 3dB bandwidth exceeding 10 GHz for the 30 μm microspiral disk. We demonstrate an open eye diagram at 15 Gbit/s with a bias current of 90 mA at a stage temperature of 15 °C.