THESIS
2016
xxvi, 189 pages : illustrations ; 30 cm
Abstract
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...[
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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.
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