Silicon Photonic Platforms and Systems for High-speed Communications

Data communication is a critical component of modern technology in our society. There is an increasing reliance on information being at our fingers tips and we expect a low-latency, high-bandwidth connection to deliver entertainment or enhanced productivity. In order to serve this demand, communications devices are being pressed for smaller form factors, higher data throughput, lower power consumption and lower cost. Similar demands exist in a number of applications including metro/long-haul telecommunications, shorter datacenter links and supercomputing. Silicon photonics promises to be a technology that will solve some of the difficulties with improving communication devices. Building photonics in silicon allows for reuse of the same fabrication technology that is used by the CMOS electronics industry, potentially allowing for large volumes, high yields and low costs. Part I of this thesis details the design of components needed in a high-speed silicon photonic platform to meet the current challenges for high-speed communications. The author’s work in modeling photodetectors resulted in improving photodetector bandwidth from 30 GHz to 67 GHz, the fastest reported at the time of publication. Details regarding the optimization and test of modulators are also presented with the first-reported 50 Gbps modulator at 1310-nm. A large scale parallel channel demonstration of high-speed silicon photonics is then presented showing the potential scalability for silicon photonics systems. A full transceiver requires a number of components other than the photodetector and modulator that are the core active pieces of a silicon photonics platform. Part II includes work on the design and test of silicon photonic components providing functionality beyond the photodetector and modulator. A novel design integrating Metal-Semiconductor Field Effect Transistors (MESFETs) into a silicon photonics platform without process change is shown. This integration enables enhanced control functionality with minimal overhead. The critical final piece for a silicon photonics platform, adding a light source, is demonstrated along with performance results of the resulting tunable, extended C-band laser. In Part III, previous work on an enhanced silicon photonics platform with complementary components is used to build a high-speed integrated coherent link and then tested with a silicon photonics-based tunable laser. The transceiver was shown to operate at 34 Gbaud dual-polarization 16-QAM for a total of 272 Gbps over a single channel. This was the first published demonstration of an integrated coherent where all of the optics were built in a silicon photonics platform

Optical frequency comb source for next generation access networks

The exponential growth of converged telecommunication services and the increasing demands for video rich multimedia applications have triggered the vast development of optical access technology to resolve the capacity bottleneck at metropolitan-access aggregations. To further enhance overall performance, next generation optical access networks will require highly efficient wavelength division multiplexing (WDM) technology beyond the capability of current standard time division multiplexed (TDM) systems. The successful implementation of future-proof WDM access networks depends on advancements in high performance transmission schemes as well as economical and practical electronic/photonic devices. This thesis focuses on an investigation of the use of optical frequency comb sources, and spectrally efficient modulation formats, in high capacity WDM based optical access networks. A novel injected gain switched comb generation technique which deliver simplicity, reliability, and cost effectiveness has been proposed and verified through experimental work. In addition, a detailed characterization of the optical comb source has been undertaken with special attention on the phase noise property of the comb lines. The potential of the injected gain switched comb source is then demonstrated in a digital coherent receiver based long reach WDM access scenario, which intends to facilitate 10 - 40 Gbit/s data delivery per channel . Furthermore, an optical scalar transmission scheme enabling the direct detection of higher order modulation format signals has been proposed and experimentally investigated