Scientists at The University of Texas at Arlington are developing a new type of ultra-thin semiconductor laser that can be integrated with mainstream electronics on common silicon substrate to increase the chip’s speed and capacity and improve energy efficiency.
UTA professor of electrical engineering Weidong Zhou will use a three-year, $600,000 grant from the U.S. Army Research Office to advance his work on printed photonic crystal and silicon lab-on-a-chip technology research. Zhou, the primary investigator on research grants totaling nearly $6 million, has been involved with more than 30 projects totaling more than $18 million since 2004.
“We are looking for devices and components to be integrated on a chip,” Zhou said. “As we address electrical injection, integration with other devices on the chip and increased power capabilities, we can begin to apply this technology to products in the medical field or in the consumer arena. These applications could include portable electronics, sensing and imaging equipment, bio applications and wearable electronics.”
Zhou’s nanophotonics lab conducts various research projects in the areas of photonic crystal infrared photodetectors, silicon-based detectors, lasers, and modulators, bio-inspired photonics, and cost-effective solar cells based on photonic crystals, semiconductor nanomembranes, quantum dots, and other nanoscale structures.
The group works on all aspects of device research, including design, simulation, fabrication, and characterization. UTA assistant professor of electrical engineering Yuze “Alice” Sun is co-principal investigator.
“Big companies like IBM and Intel are using this technology for high-performance computing centers,” Zhou said in a UTA release. “The big push now is for the next big thing: smaller, faster, and less and less power consumption.”
Zhou also recently received a three-year $935,000 grant from the U.S. Air Force Office of Scientific Research to fund exploration of extreme energy efficient lasers, in collaboration with Profs. Shanhui Fan at Stanford and Xiuling Li at the University of Illinois Urbana-Champaign.
The projects highlight the increasingly important role The University of Texas at Arlington is playing in laser technology research and how lasers work on semiconductors.
A Fellow of the International Society for Optical Engineering, Zhou holds three issued patents related to photonics technology, and has been a co-author of more than 270 journal articles and conference presentations.
A paper published online last month in Nature’s Scientific Reports titled “Printed Large-Area Single-Mode Photonic Crystal Bandedge Surface-Emitting Lasers on Silicon“ outlines Zhou’s findings from related research supported by grants from the National Science Foundation, the Air Force Office of Scientific Research and the U.S. Army Research Office.
Zhou and his research team reported on two types of lasers operating at different temperatures, with detailed modal analysis revealing lasing mode matches with the estimated lasing gain threshold conditions. They say their demonstration promises a hybrid laser sources on silicon toward three-dimensional (3D) integrated silicon photonics for on-chip wavelength-division multiplex systems. This technology will have a wide range of applications in computing, communications, sensing, imaging, and other fields.
The investigators reported that their results indicate that combining the transfer printing process and the photonic crystal bandedge cavity offers a simple and flexible method to realize single mode high power lasers for large-scale silicon-based photonic integration.
The researchers concluded that further optimization of the cavity design and improved fabrication quality can lead to realization of electrically-pumped lasers operating at room temperature with potential 2D multi-wavelength arrays for on-chip multi-layer wavelength-division multiplexing (WDM) — a technology that multiplexes multiple optical carrier signals onto a single optical fiber by using different wavelengths of laser light — yielding WDM systems with desired spectral, spatial, and energy-efficiency.
The UTA release notes that Zhou’s previous research led to innovations that removed roadblocks to putting optical technology on a silicon chip, and that he has developed a membrane laser less than one micron thick that is compatible with planar Complementary Metal Oxide Silicon platforms — the building blocks for all electronics — that can be easily integrated with current platforms. The key innovation is integration of certain compound semiconductor material with a silicon photonic crystal cavity, thereby allowing a laser to be built directly on a silicon chip next to other electrical components, leading to higher speed and higher efficiency.
The initial application of Zhou’s laser discoveries will be in computers and data centers, where higher bandwidth and transfer rates at lower energy outputs is a constant goal.
Zhou’s UTA research group is pursuing various innovative membrane laser architectures for extreme energy-efficient computing and communication systems, and the Zhou Lab will apply his new grant funding to continued innovation development in high-performance membrane lasers. One of these was described in a 2012 Nature Photonics article titled “Transfer printing stacked nanomembrane lasers on silicon,“ in which Zhou and his co-authors observed that realization of silicon-based light sources has been the subject of a major research and development effort worldwide.
They explain that such sources may help make integrated photonic and electronic circuitry more cost-effective, with higher performance and greater energy efficiency, and that the hybrid approach is an attractive route in the development of silicon lasers because of its potential for high-efficiency.
“Hybrid lasers with good performance have been reported that are fabricated by direct growth or direct wafer-bonding of the gain medium to silicon,” the investigators noted. “Here, we report a membrane reflector surface-emitting laser on silicon that is based on multilayer semiconductor nanomembrane stacking and a stamp-assisted transfer-printing process. … We also demonstrate high-finesse single- or multi-wavelength vertical laser cavities.”
The UTA Electrical Engineering Department is a major faculty of UTA’s College of Engineering, which recently became the third-largest in Texas with an enrollment of more than 7,000. The faculty members working in the photonics field include National Academy of Inventors Charter Fellow Robert Magnusson and Michael Vasilyev, who is a Fellow of The Optical Society.
In the release, Khosrow Behbehani, dean of the UTA College of Engineering, commends Zhou’s laser and photonics innovations as an example of the university’s work to advance the Global Environmental Impact component of UTA’s Strategic Plan 2020: Bold Solutions initiative, with the school rapidly becoming the model for what a 21st century urban research university should be.
This strategic plan, with its four broad themes, Health and the Human Condition, Sustainable Urban Communities, Global Environmental Impact, and Data-Driven Discovery, crystallizes the urban research university model and sets a path to excellence in research, teaching, and community engagement.
“As technology becomes pervasive in our everyday life from the cars we drive to our clothing, the ability to make smaller, more power-efficient components becomes more valuable,” Behbehani said. “Zhou’s research could be truly groundbreaking and lead to many future discoveries.”