Optical interconnects have recently emerged as a promising solution to address the bandwidth and power-consumption requirements in next-generation high-performance computing and intra-datacenter applications as they offer a high data throughput with potentially low power consumption. Leveraging the mature silicon complementary metal-oxide-semiconductor (CMOS) fabrication technology, silicon photonics offers a unique potential platform to build low-cost, high-speed, energy-efficient, compact devices and modules for intra-datacenter optical interconnects which require a link distance up to ~10 km. One of the key building blocks for such a photonics link is the on-chip light source emitting at Telecom/Datacom wavelengths. As silicon is transparent in these wavelengths, other direct...[ Read more ]

Optical interconnects have recently emerged as a promising solution to address the bandwidth and power-consumption requirements in next-generation high-performance computing and intra-datacenter applications as they offer a high data throughput with potentially low power consumption. Leveraging the mature silicon complementary metal-oxide-semiconductor (CMOS) fabrication technology, silicon photonics offers a unique potential platform to build low-cost, high-speed, energy-efficient, compact devices and modules for intra-datacenter optical interconnects which require a link distance up to ~10 km. One of the key building blocks for such a photonics link is the on-chip light source emitting at Telecom/Datacom wavelengths. As silicon is transparent in these wavelengths, other direct bandgap materials, like III-V compound, need to be integrated in this platform for the light emission.

In this thesis, we demonstrate and propose a number of on-chip light sources on III-V and III-V-on-silicon substrate including (i) direct-modulated waveguide-integrated microspiral disk lasers, (ii) hybrid silicon waveguide-integrated microspiral disk lasers and (iii) a 2-channel hybrid silicon transmitter using a microspiral disk laser as a single element.

We investigate direct-modulated waveguide-coupled microspiral disk lasers on InP substrate. 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. 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 3 dB 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.

We develop the hybrid silicon microspiral disk lasers using benzocyclobutene (BCB) die-to-die bonding and oxide multiple-dies-to-wafer bonding. We numerically and experimentally investigate different silicon microspiral disk cavities directly coupled with an output-waveguide, with III-V multiple-quantum-well (MQW) gain mediums of different circular microdisk geometries vertically coupled on the top. We demonstrate around or below a 10 mA threshold with a maximum output power in the level of 100 μW in the waveguide under pulsed injection at room temperature. We obtain unidirectional lasing output with CW/CCW suppression ratio up to 20.8dB. A 2-channel laser array with 12.9nm spacing multiplexed into a single waveguide output is also demonstrated under pulsed injection. Upon room temperature continuous-wave (cw) injection, we demonstrate a device with a lasing threshold of ~10mA.