Bio

Kun (Linda) Li is a PhD candidate in the Department of Electrical Engineering and Computer Sciences at University of California Berkeley, advised by Prof. Connie Chang-Hasnain. Prior to joining graduate school, she received her B.S. degree from Optical Engineering of Zhejiang University in China (2006-2010). She had one year of exchange experience in University of Hong Kong (2008-2009). Kun’s main research interests focus on III-V nanostructures directly grown on silicon for integrated optoelectronics, and vertical-cavity surface emitting laser (VCSEL) with high-contrast grating (HCG) structure for optical communication and imaging. Her skills include optical characterization, semiconductor fabrication, and optoelectronic device modeling. She received Lam Research Graduate Fellowship (2014) to award her performance in the field of semiconductors. Besides research, Kun is also active in a variety of education, outreach, and mentoring programs, including Girl Scouts, Expanding Your Horizon, and Girls in Engineering. Kun has won the Outstanding Graduate Student Instructor Award at UC Berkeley (2014).

III-V compound semiconductor lasers for optical communication and imaging

III-V compound semiconductor lasers for optical communication and imaging

My research projects focus on III-V compound semiconductor lasers to generate and manipulate light, with both bottom-up and top-down approaches, for applications in optical communications, biological imaging, ranging and sensing.

As microprocessors become progressively faster, chip-scale data transport becomes progressively more challenging. Optical interconnects for inter- and intra-chip communications are required to reduce power consumption and increase bandwidth. Lightwave devices have traditionally relied on III-V compound semiconductors due to their capacity for efficient optical processes. Growing III-V materials from the bottom up opens a pathway to integrating superior optoelectronic properties with the massive existing silicon-based infrastructure. Our approach of self-assembling III-V nanostructures on silicon in a novel growth mode has bypassed several roadblocks and achieved excellent single crystalline quality with GaAs and InP based materials. I have developed a methodology to evaluate optical properties of InP nanostructures, and demonstrated its superior surface quality, which are critical for optoelectronic devices.

I also make another type of micro-scale semiconductor lasers from the top down, which is called vertical-cavity surface-emitting lasers (VCSELs). They are key optical sources in optical communications, with the advantages of lower power consumption, lower-cost packaging, and ease of fabrication and testing. Our group has demonstrated a revolutionary single-layer, high-index contrast sub-wavelength grating (HCG), and implemented it as a reflection mirror in VCSEL. Compared with conventional VCSEL mirrors (DBRs), the seemingly simple-structured HCG provides ultra-broadband high reflectivity, compact size and light weight, high-tolerant and cost-effective fabrication process. I mainly work on the development of wavelength-tunable 850nm and 1060nm HCG-VCSELs. These monolithic, continuously tunable HCG-VCSELs will present extraordinary performance in applications such as wavelength-division-multiplexed (WDM) optical network, light detection and ranging. Its potential wide reflection band and fast tuning speed will also be highly promising for high-resolution, real-time imaging in optical coherent tomography (OCT).