Title

Recent advances in green and blue laser diodes fabricated on nonpolar/semipolar GaN substrates

Speaker

Dr. James W. Raring, Vice President of Laser Engineering, Soraa Inc.

Abstract

Fueled by rapid progress toward the commercialization of the direct-diode green laser and the introduction of innovative new display technologies based on blue-laser diode pumped green phosphors, we are entering a paradigm shift for projection displays that will require a massive deployment of GaN-based laser diodes. By combining direct green laser diodes with the already available red and blue laser diodes, a compact, highly-efficient, low-cost R-G-B laser-based light engine is realized to enable brilliant miniature displays with enhanced viewing flexibility. These miniature displays, or so-called pico projectors, will see proliferation into smart-phones, cameras, and other handheld devices. In parallel to the rapid progress in these small scale displays, we are in the midst of a swift technology shift in high lumen output projectors serving markets such as desktop projectors, home theater, digital advertising, and cinema where conventional bulb illumination is being replaced with laser diode based illumination. The cumulative result of these new consumer applications requiring GaN-based blue and green laser will drive the next boom in laser diode demand.

Soraa Inc. is pursuing the unconventional nonpolar and semipolar orientations of bulk GaN for the development of high performance green and blue laser diodes. These novel orientations provide superior physics over the conventional c-plane orientation, which suffers from internal polarization fields that spatially separate the electron and hole wavefunctions in the light emitting quantum well regions. Such internal fields reduce the radiatiave recombination efficiency and introduce design constraints on the epitaxial and device structure. Free from these restrictions, Soraa is making rapid progress towards the commercialization of blue and green laser diodes with the demonstrations of the first true green (525nm) continuous wave laser diode and world-class power and efficiency from single-mode blue laser diodes.

Biography

Dr. Raring received his Ph.D. in Materials Science from the University of California, Santa Barbara in 2006 where he developed an advanced InP-based photonic integration scheme by combining MOCVD regrowth with quantum well intermixing. Leveraging this novel monolithic integration platform, he demonstrated the first single-chip 40 Gb/s optical transceiver. After completing his work at UCSB, Dr. Raring joined Sandia National Laboratories as a Senior Member of Technical Staff in the photonic integrated circuit (PIC) group where he continued development of high-functionality InP-based devices.

In 2008, Dr. Raring joined Soraa Inc. as a founding employee where he has helped grow the company and establish key infrastructure such as the epitaxial growth capabilities. As Vice President of Laser Engineering, he and the Soraa team are developing state-of-the-art blue and green InGaN-based laser diodes fabricated on nonpolar/semipolar GaN substrates towards commercialization. Key achievements for the Soraa laser engineering team include the demonstration of the first true green (525nm) continuous-wave laser diode, record wall-plug efficiency (>23%) from single-mode blue laser diodes, and over 4.5W from a blue laser bar. With over 10 years of experience in compound semiconductor and optoelectronic device technology, Dr. Raring has authored or co-authored over 100 technical papers and conference presentations.

About Soraa:
Soraa is a rapidly expanding semiconductor company leveraging fundamental materials advances. Soraa is commercializing energy saving products such as a new generation of green and blue semiconductor lasers for consumer, biomedical, defense, and industrial applications.

Soraa was founded in 2008 by world renowned laser diode and LED pioneers Professors Shuji Nakamura, Steven Denbaars and James Speck of University of California, Santa Barbara. The company received initial funding from Khosla Ventures and the management team is comprised of high tech industry veterans. Soraa is vertically integrated and located in Santa Barbara and Fremont, CA.