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Brad Petersen
Director of
Communications
2052 ECE Building
306 N. Wright Street
Urbana, IL 61801
Phone: (217) 244-6376
bradp@illinois.edu

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Meg Dickinson
Communications Specialist
2016 ECE Building
306 N. Wright Street
Urbana, IL 61801
Phone: (217) 300-6664
megd@illinois.edu

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Recent News

New ECE class gives students an in-depth look at the engineering process

New ECE class gives students an in-depth look at the engineering process

Starting this semester, ECE ILLINOIS will offer students an opportunity to study the engineering design process and possibly get a head start on their Senior Design projects with a new class called ECE 398, Special Topics in ECE.

ECE Illinois researchers develop new, higher-speed laser

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By Lauren Eichmann, ECE Illinois
July 23, 2007

  • ECE Illinois researchers have developed a new laser configuration, the composite-resonator vertical-cavity laser (CRVCL), that could potentially achieve higher speeds than a traditional vertical-cavity surface-emitting laser (VCSEL).
  • Prof. Kent Choquette said he has been working for more than a decade to discover a way to increase the modulation bandwidth, and is excited by his team‚Äôs progress.
Chen Chen
Chen Chen

ECE Illinois researchers have developed a new laser configuration that could potentially achieve higher speeds than a traditional vertical-cavity surface-emitting laser (VCSEL). The composite-resonator vertical-cavity laser (CRVCL), which currently has a modulation bandwidth of 12.5 GHz, has the capability to achieve up to 40 GHz, according to ECE Professor Kent Choquette, a Sony Faculty Scholar, and graduate student, Chen Chen.

Fig. 1 Device schematics for VCSEL and CRVCL.
Fig. 1 Device schematics for VCSEL and CRVCL.

According to Chen, the emergence of VCSELs represents a significant advance in optoelectronics and their applications. "CRVCLS are built upon VCSEL structures. Through a higher level of device integration, a VCSEL has evolved from a device with a single optical cavity and two electrical terminals to a CRVCL with two optically-coupled electrically-separately cavities and three electrical terminals (refer to Fig. 1)," he said. "CRVCLS gain additional functionalities and flexibilities over VCSELS, and thereafter they may be used for even wider applications.

Unlike a VCSEL, a CRVCLís optical properties, such as threshold current, slope efficiency, and maximum light output, can be changed through one cavity while the electrical current into the other cavity is held constant, Chen said. (see Fig. 2)

Fig. 2 Measurement of light output versus current in the bottom cavity of a CRVCL at different dc voltage across the top cavity (Left). This measurement can also be illustrated in another way as light output power versus voltage across the top cavity of a CRVCL at different current levels in the bottom cavity (Right).
Fig. 2 Measurement of light output versus current in the bottom cavity of a CRVCL at different dc voltage across the top cavity (Left). This measurement can also be illustrated in another way as light output power versus voltage across the top cavity of a CRVCL at different current levels in the bottom cavity (Right).
Kent D. Choquette
Kent D. Choquette

Choquette said he has been working for more than a decade to discover a way to increase the modulation bandwidth, and is excited by his teamís progress. The teamís post-deadline research paper was one of only 24 papers recognized at the Conference on Lasers and Electro-Optics (CLEO) in May at the Baltimore Convention Center. "To get recognized at CLEO, which is the premiere lasers and applications conference in the world, is a big deal. Itís very competitive," said Choquette.

Choquette, who has been at Illinois nearly eight years and is the interim director of the Micro and Nanotechnology Lab, explained that the team is concentrating on ultimately achieving low-cost, high-performance lasers with more functionality. "If we can make lasers modulate faster, with lower power, there will be higher performance in optical networks," he said. "Cell phones and computers will work better. It directly enables the information network and moves information faster."

Chen has been focusing on CRVCLs for two years, during which he has spent a great deal of time fabricating the structure, said Choquette. Although Chen said he is happy about the recognition he and his colleagues in the Photonic Device Research Group have received, he acknowledged that it is still early in development and there may be some obstacles ahead. "CRVCLs contain very rich device physics, many of which arenít fully understood," said Chen. "I think one of the greatest challenges is to relate the device characteristics, what I can see, to the physics - what it is really happening," said Chen.

Choquette said he is impressed with all the research students have been doing at Illinois. "Weíre doing things here in an academic lab that I was doing in a national lab a few years ago," he said.

Portions of this work are funded by the National Science Foundation.

Editor's note: media inquiries should be directed to Brad Petersen, Director of Communications, at bradp@illinois.edu or (217) 244-6376.

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