Distinguished Professor Marek Osinski, (Committee Chair), ECE 

Professor Ganesh Balakrishnan, ECE 

Professor Francesca Cavallo, ECE

Professor Nathan Jackson, NSMS

InP-based platforms dominate the development of Photonic Integrated Circuits (PICs) that are designed for the telecommunication wavelength of 1550 nm. A typical photonic integrated circuit contains multiple optical components on the same chip. However, a PIC that utilizes monolithic integration can reduce the manufacturing complexity, power consumption, form factor, weight, and optical propagation loss between the circuit elements. Moreover, such a system can enhance bandwidth and stability. Over several years, the design and simulation of a PIC for ultra high-speed modulation has been conceived. However, till now, that system could not be realized due to the complexity involved in the fabrication process development. Therefore, for the first time, successful fabrication of this monolithically integrated InP-based PIC used for ultra high-speed modulation, was demonstrated.  

The design of the PIC required the photonic components of this device to be created by deep etching of an epitaxially-grown multilayer structure. Therefore, a novel dry etching process was developed to produce very high aspect ratio (HAR) features. This process not only involved development of dry etch chemistry but also the engineering of a metal mask structure. The next step of the challenge was to use a polymer-based material that would have two functions:  cladding for the etched photonic components and a stable mechanical structure that would support the electrical fanouts. A novel scheme was engineered to apply SU-8 as the polymer that fulfils both the roles and helps to realize functioning devices. Preliminary I-V and CW characterization was performed on the device to verify the basic functionality. This work will be a steppingstone for performing high-speed modulation, performance analysis, and design improvisation for the next generation of the fabricated PICs.