Gigascale Silicon Photonic Transmitters Integrating HBT-based Carrier-injection Electroabsorption Modulator Structures.
Abstract: Demand for
more bandwidth is rapidly increasing, which is driven by data intensive applications
such as high-definition (HD) video streaming, cloud storage, and terascale computing
applications. Next-generation high-performance computing systems require power efficient
chip-to-chip and intra-chip interconnect yielding densities on the order of 1Tbps/cm2.
The performance requirements... read moreof such system are the driving force behind the development
of silicon integrated optical interconnect, providing a cost-effective solution for
fully integrated optical interconnect systems on a single substrate. Compared to
conventional electrical interconnect, optical interconnects have several advantages,
including frequency independent insertion loss resulting in ultra wide bandwidth and
link latency reduction. For high-speed optical transmitter modules, the optical
modulator is a key component of the optical I/O channel. This thesis presents a silicon
integrated optical transmitter module design based on a novel silicon HBT-based carrier
injection electroabsorption modulator (EAM), which has the merits of wide optical
bandwidth, high speed, low power, low drive voltage, small footprint, and high
modulation efficiency. The structure, mechanism, and fabrication of the modulator
structure will be discussed which is followed by the electrical modeling of the
post-processed modulator device. The design and realization of a 10Gbps monolithic
optical transmitter module integrating the driver circuit architecture and the HBT-based
EAM device in a 130nm BiCMOS process is discussed. For high power efficiency, a 6Gbps
ultra-low power driver IC implemented in a 130nm BiCMOS process is presented. The driver
IC incorporates an integrated 27-1 pseudo-random bit sequence (PRBS) generator for
reliable high-speed testing, and a driver circuit featuring digitally-tuned pre-emphasis
signal strength. With outstanding drive capability, the driver module can be applied to
a wide range of carrier injection modulators and light-emitting diodes (LED) with drive
voltage requirements below 1.5V. Measurement results show an optical link based on a
70MHz red LED work well at 300Mbps by using the pre-emphasis driver module. A traveling
wave electrode (TWE) modulator structure is presented, including a novel design
methodology to address process limitations imposed by a commercial silicon fabrication
technology. Results from 3D full wave EM simulation demonstrate the application of the
design methodology to achieve specifications, including phase velocity matching,
insertion loss, and impedance matching. Results show the HBT-based TWE-EAM system has
the bandwidth higher than 60GHz.
Thesis (Ph.D.)--Tufts University, 2015.
Submitted to the Dept. of Electrical Engineering.
Advisor: Valencia Joyner Koomson.
Committee: Mohammed Afsar, Mark Cronin-Golomb, and Ronald Knepper.
Keyword: Electrical engineering.read less