Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Etching holes in vertical-cavity surface-emitting lasers creates better beam

11.02.2004


Researchers at the University of Illinois at Urbana-Champaign have found a way to significantly improve the performance of vertical-cavity surface-emitting lasers by drilling holes in their surfaces. Faster and cheaper long-haul optical communication systems, as well as photonic integrated circuits, could be the result.



Low-cost VCSELs are currently used in data communication applications where beam quality is of little importance. To operate at higher speeds and over longer distances, the devices must function in a single transverse mode with a carefully controlled beam.

"These characteristics are normally found only in very expensive lasers, not in mass-produced VCSELs," said Kent D. Choquette, an Illinois professor of electrical and computer engineering and a researcher at the university’s Micro and Nanotechnology Laboratory. "By embedding a two-dimensional photonic crystal into the top face of a VCSEL, however, we can accurately design and control the device’s mode characteristics."


Choquette and his colleagues -- Illinois graduate students Aaron J. Danner and James J. Raftery Jr., and scientist Noriyuki Yokouchi at the Furukawa Electric Co. in Yokohama, Japan -- will report their findings in the Feb. 16 issue of the journal Applied Physics Letters.

The two-dimensional photonic crystal, created by drilling holes in the semiconductor surface, introduces a periodic change in the index of refraction, Choquette said. The holes represent regions of low refractive index, surrounded by semiconductor material where the index is higher. A particular combination of refractive indices will produce a single-mode waveguide that permits only one transverse wave of the laser beam to propagate.

"Our photonic crystal consists of a triangular array of circular holes that have been etched into the top of a VCSEL," Choquette said. "Because the index variation has to be on the length scale of light, the periodicity of the holes must be on the order of several hundred nanometers."

To create such a precise array of holes, the researchers first lithographically define the desired pattern into a silicon dioxide mask layer on the semiconductor surface using focused-ion beam etching. The holes are then bored into the semiconductor material using inductively coupled plasma etching.

"By selectively varying parameters such as depth, diameter and spacing of the holes, we can control the modal characteristics of the laser," Choquette said. "This means we can accurately design and fabricate single-mode VCSELs for high-performance optical communication systems."

The next step, he said, is to push VCSEL performance toward higher power by considering designs that are much larger in diameter.

"Looking beyond that, we also have fundamental problems with high-speed data communication on our circuit boards and in our chips," Choquette said. "This is a technology that could serve as the foundation for a new way of looking at optical interconnects and photonic integrated circuits."


###
The National Science Foundation and Defense Advanced Research Projects Agency funded the work.

James E. Kloeppel | UIUC
Further information:
http://www.news.uiuc.edu/news/04/0210crystals.html

More articles from Physics and Astronomy:

nachricht New material for splitting water
19.06.2018 | American Institute of Physics

nachricht Carbon nanotube optics provide optical-based quantum cryptography and quantum computing
19.06.2018 | DOE/Los Alamos National Laboratory

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

Im Focus: Photoexcited graphene puzzle solved

A boost for graphene-based light detectors

Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Carbon nanotube optics provide optical-based quantum cryptography and quantum computing

19.06.2018 | Physics and Astronomy

How to track and trace a protein: Nanosensors monitor intracellular deliveries

19.06.2018 | Life Sciences

New material for splitting water

19.06.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>