Looking to leap forward on laser and photodetector technologies

August 6, 2010

A team of Arizona State University researchers will get support from the U.S. Department of Defense to aid development of the next generations of lasers and infrared photodetectors.

The technology is widely employed in sensing and imaging for an array of defense and commercial applications. Download Full Image

The work will be funded by an Army Research Office grant through the defense department’s Multidisciplinary University Research Initiative (MURI) program, which supports science and engineering endeavors involving research and technology development considered vital to national interests.

ASU’s Yong-Hang Zhang, David J. Smith and Shane Johnson will combine expertise in electrical engineering, materials science and physics to contribute to a project in which they will collaborate with colleagues at University of Illinois at Urbana-Champaign, the Georgia Institute of Technology and the University of North Carolina.

The entire project has been approved for a grant of $6.25 million over five years. ASU’s team has been awarded $2.34 million for its part of the effort.

Zhang is a professor and Johnson is a senior research scientist in the School of Electrical, Computer and Energy Engineering, one of ASU’s Ira A. Fulton Schools of Engineering.

Smith is an ASU Regents’ Professor in the Department of Physics in ASU’s College of Liberal Arts and Sciences.

They’ll focus on deepening knowledge of the basic properties of materials used to construct lasers and infrared photodetectors. They’ll study the origins of defects in the materials and explore ways to reduce them.

Understanding how defects form at the nanometer scale will enable improvements in these materials, opening the path to advances in semiconductors, infrared photodetectors and imaging systems, Johnson said.

This is the third MURI program grant awarded to ASU researchers in the past several years in semiconductor optoelectronics and photonics. There were more than 150 full proposals for fiscal 2010 MURI grants. Only 32 were chosen for funding.

The project in which the ASU team is involved is the only one selected this year in the area of laser and photodetector materials research.

“This indicates national recognition of the research efforts at ASU in these areas,” Zhang said.

“I’m very pleased to see our team selected, because competition for this particular MURI grant was very strong,” Zhang said. “Many of the teams competing are led by outstanding scientists.”

Zhang, Smith and Johnson will strive to better understand and improve the physical and structural properties of antimonide-based compound semiconductor materials. Those materials offer the potential to produce very high-performance infrared photodetectors and lasers, Johnson said.

Specifically, they’ll study superlattice systems that consist of two or more materials that are intentionally arranged in alternating semiconductor layers several nanometers thick.

The superlattice structures combined with an antimonide material system can give engineers “additional degrees of freedom when selecting for color and performance in infrared photodetectors and lasers,” Johnson said. 

The ASU team has a strong track record in this area. Zhang did pioneering work on superlattices for infrared laser applications while at the prominent Hughes Research Laboratories, and has been collaborating with Johnson and Smith on this research since he joined ASU in 1996. Smith has decades of experience studying structural properties of semiconductor superlattices.

Joe Kullman

Science writer, Ira A. Fulton Schools of Engineering


Mobile technology transforms rehearsal process

August 6, 2010

With help from mobile technology, artists who once were considered triple threats as actors, singers and dancers now can add writer, producer and director to their résumé. Techno gadgets quickly are becoming more of a necessity than a distraction to artist entrepreneurs who constantly have to adapt their creative processes to advance their craft.

A group of ASU">http://herbergerinstitute.asu.edu/">ASU Herberger Institute graduate students are offering a behind-the-scenes peek at the rehearsal process, which they now are digitally recording with the help of their cell phones – making the act of taking notes with a legal pad and a No. 2 pencil a thing of the past. Download Full Image

Enter Stjepan Rajko, who simply was fulfilling a class assignment for a School">http://dance.asu.edu/">School of Dance "Performance & Technology" class about five years ago. The dance graduate student envisioned software that primarily was designed to help a choreographer working alone in a studio to play music and record rehearsal video (with playback) in response to voice commands.

“The idea began as a ‘mockumentary’ about a helpful software system that didn't yet exist,” Rajko said.

Three years later, Rajko was leading a cross-disciplinary, graduate-student team that designed a rough model, and developed the Rehearsal">http://vimeo.com/5158091">Rehearsal Assistant, a general-purpose audio recording Android app for a mobile phone that works in tandem with a computer. Rajko explained that its main element is that audible notes are time-stamped, and can be played back in conjunction with a video recording of a rehearsal. He believes the time-stamp feature enables performers to better understand the context and meaning of each note.

 “This is useful for a dance or theater rehearsal, but it can also be used for a rehearsal of a speech or presentation, or for sports practice,” Rajko said. “A journalist could use the system to annotate an event they are observing and then review it later. A researcher could use it to annotate an experiment as it unfolds.”

Since its release in spring 2009, the Rehearsal Assistant app has been downloaded nearly 60,000 times.

The app’s development process began with Rajko, who in early spring 2008, teamed up with Jessica Mumford, a fellow dance graduate student. Mumford and Rajko then approached Christopher Martinez, a graduate student in the Herberger Institute School">http://ame.asu.edu/">School of Arts, Media and Engineering, to work on the app’s music and visual design. Martinez and his wife already were working with Mumford on her online and live performance work, titled “Case Study.”

“Rehearsal Assistant is an example of artists who are creating a tool for the arts,” Martinez said. “These tools also have broader social and cultural implications that are a result of their flexibility to be employed for art-making as well as for other uses. Our team’s passion is about facilitating and promoting the creative process both through works of art, as well as the development of tools that are used as part of the creative process.”

The team’s collaborative spirit on the Rehearsal Assistant tool not only helps its members exercise creative freedoms, and streamline and enhance rehearsal experiences, but further eliminates the perception that art and technology exist in disconnected universes.

“By merging art and technology practices together, we open doors to new ways of thinking about each discipline,” Mumford said. “Both art and technology require creative thinking, structure, awareness of the potential audience, flexibility, the ability to evolve and adapt. Even though computer science and engineering emphasize logic and structure, there is still creativity and imagination involved.”

The Rehearsal Assistant app is a concrete example that practices of art and technology are not separate, but their convergence is crucial to expanding cross-disciplinary collaboration. What began as a simple classroom assignment revolutionizes how Rehearsal Assistant users think about and approach their craft. User feedback is essential to the app’s advancement and is fueling the team’s enthusiasm.

“It has been wonderful to hear back from users and learn that they are excited about it and finding it useful,” Rajko said. “Once the system is robust enough to be tested and used on a broader scale, we will try to find local artists and researchers that are interested in using it, and work with them to make sure Rehearsal Assistant meets their needs. Our hope is that the system will help them make their process more effective.”

Wendy Craft

Marketing and communications manager, Business and Finance Communications Group