Cmos Compatible Key Engineering Devices For High Speed Silicon Based Optical Interconnections PDF Download

"Global IP traffic will continue to grow in the foreseeable future. Different applications are driving demand for increased capacity such as cloud based services, video streaming services, and big data.Since 2008, most Internet traffic has originated or terminated in datacenters. As a result, datacenters have experienced unprecedented traffic increases, where datacenter traffic will reach more than 20.6 zettabytes by 2021, i.e., 3-fold increase since 2016. In response to demands to support capacity increases, there are significant worldwide research and commercialization efforts that are being directed toward developing high speed intra- and inter-datacenter optical interconnects (DCIs). Different material platforms are used to build optical transceivers including the silicon photonics (SiP) platform. The SiP platform has the potential to build compact, high yield, high performance, and low cost complementary metal oxide semiconductor (CMOS) compatible transceivers. In this thesis, we explore devices and circuits for optical DCIs. This thesis can be divided into three parts. In the first part, we develop and demonstrate passive and active SiP components which are essential in photonic integrated circuits (PICs) for optical transceivers. The first device is a 3-dB beam splitter based on multi-mode interference (MMI), where we present the device design and wafer-scale experimental results. Then, we include subwavelength gratings into an asymmetric MMI to enable compact, large bandwidth, and different splitting ratios. Using cascaded MMIs, we design a C-band polarization beam splitter for coherent PICs, where we demonstrate the advantages of using a cascaded MMI design in improving the device extinction ratio. Next, we present the detailed design and experimental results of a high yield and low insertion loss polarization splitter and rotator. Different variations of this design are demonstrated aiming at different performance metrics and operating bands. Finally, we present a variable optical attenuator based on a Mach-Zehnder interferometer structure where a substrate undercut is added to the design to enable low power consumption. In the second part, we present PICs for 200 Gb/s and 400 Gb/s intra-datacenter optical interconnects. First, a 4-lane SiP transmitter is demonstrated based on four parallel Mach-Zehnder modulators (MZMs). The crosstalk between the four MZMs is studied using small-signal and large-signal modulation. Driving the four MZMs simultaneously, 400 Gb/s aggregate rate can be achieved using relatively low voltage swing and simple digital signal processing (DSP). Then, we explore 200 Gb/s transmitters based on dual parallel multi-electrode MZMs (MEMZMs) to generate the PAM4 signal optically which results in a better signal to noise ratio compared to the electrical generation. Finally, we exploit the other polarization dimension by demonstrating a dual-polarization transmitter in a stokes vector direct detection experiment. More than 200 Gb/s can be achieved using this transmitter which doubles the capacity used for a classical intensity modulation/direct detection system and renders a better scalable approach for bitrates beyond 400 Gb/s. In the last part, we report system-level demonstrations targeting DCI applications. First, we present a single wavelength and polarization PAM4 transmission experiment using state of the art digital-to-analog converters (DACs), analog-to-digital converters (ADCs), and a lithium niobate MZM. Then, we present the first demonstration of a 400 Gb/s transmitter optical sub-assembly (TOSA) on the coarse wavelength division multiplexing (CWDM) grid. The TOSA performance is studied versus several parameters. Results show that we can achieve more than 600 Gb/s over 20 km of single mode fiber (SMF) without optical amplification"--