Integrated Electronic-Photonic Systems: From High-Resolution Synthesis To Compact Phased Arrays

Silicon-based integrated electronics drastically changed many areas from communications to healthcare, mainly due to the high yield and low cost of large-scale production of complex systems with very small footprints. More recently, silicon photonics has also been used to integrate bulky, expensive, and power hungry optical systems. Low propagation loss and high optical confinement of silicon photonic waveguides have enabled many applications from imaging to signal generation. Since both electronic and photonic components can now be co/hybrid integrated, there are a large number of application that are enabled by using integrated electronic-photonic systems. Electronic-assisted photonic systems, benefit from complex control electronics to implement photonic systems with superior performance compared to conventional implementations. Similarly, photonic-assisted electronic systems take advantage from the large bandwidth available at optical frequencies as well as low-loss optical interconnects to enhance the speed and power consumption of electronic systems. In this thesis, three examples of integrated electronic-photonic systems are presented. Starting with synthesis of optical signals, a partially integrated high-resolution optical frequency synthesizer is demonstrated where an integrated electro-optical phase-locked loop is used to phase-frequency lock a highly tunable laser to a stabilized optical frequency comb. The system is capable of synthesizing optical frequencies around 1550 nm over a range of 5 THz with sub-Hz resolution. Next, we benefit from the large bandwidth and low loss of photonic integrated components to implement a nanophotonic near-field microwave imager. The imager up-converts the received microwave signals reflected from a metallic object to optical frequencies and optically processes the signals to form the corresponding image of the object. The 121-pixel imager achieves 4.8° spatial resolution with orders of magnitude smaller size than the benchtop implementations and a fraction of the power consumption. Finally, solid-state optical beam steering using novel integrated optical phased arrays is presented. We address the challenge of realizing optical phased arrays with very small element spacing by reducing the number of phase shifters required for 2-D beam steering as well as benefiting from a photonic fabrication process with two optical device layers to implement very compact optical elements. Using these novel methods, an optical phased array with 3 um element spacing and beam steering range of about 23° is implemented