PhD Defense: "Hybrid Silicon Photonic Integration Using Quantum Well Intermixing"

Siddharth R. Jain

October 4th (Thursday), 10:00am
Elings Hall, Room 1605

With the push for faster data transfer across all domains of telecommunication, optical interconnects are transitioning into shorter range applications such as in data centers and personal computing. Silicon photonics, with its economic advantages of leveraging well-established CMOS manufacturing facilities, is considered the most promising approach to further scale down the cost and size of optical interconnects for chip-to-chip communication. Intrinsic properties of silicon however limit its ability to generate and modulate light, both of which are key to realizing on-chip optical data transfer. The hybrid silicon approach directly addresses this problem by using molecularly bonded III-V epitaxial layers on silicon for optical gain and absorption. This technology includes direct transfer of III-V wafer to a pre-patterned silicon-on-insulator (SOI) wafer. Several discrete devices for light generation, modulation, amplification and detection have already been demonstrated on this platform.

As in the case of electronics, multiple photonic elements can be integrated on a single chip to improve performance and functionality. However, scalable photonic integration requires the ability to control the bandgap for individual devices along with design changes to simplify fabrication. In the research presented here, quantum well intermixing is used as a technique to define multiple bandgaps for integration on the hybrid silicon platform. Implantation induced disordering is used to generate four bandgaps spread over 120+ nm. By combining these selectively intermixed III-V layers with pre-defined gratings and waveguides on silicon, we fabricate distributed feedback (DFB), distributed Bragg reflector (DBR), Fabry-PĂ©rot (FP) and mode-locked lasers (MLL) along with photodetectors, electro-absorption modulators (EAM) and other test structures, all on a single chip. We demonstrate a broadband DFB laser source with CW operational lasers over a 200 nm bandwidth. Some of these lasers are integrated with EAMs with a 3-dB bandwidth above 25 GHz, thus realizing a coarse WDM transmitter on silicon.

About Siddharth R. Jain:

photo of siddharth jain Siddharth R. Jain received his B.E. in electrical engineering from Anna University, India, in 2007 and his M.S. in electrical and computer engineering from the University of California, Santa Barbara, in 2009, where he is currently working towards a PhD under Dr. John Bowers. His research interests include photonic integration on the hybrid silicon platform and quantum well intermixing based integration technologies. He privately believes that laser sword fights will be a reality some day.

Hosted by: Professor John Bowers