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UCLA Claims First Silicon Laser

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11/5/2004
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LOS ANGELES -- Researchers at UCLA have demonstrated the first silicon laser, which could lead to more effective biochemical detection, secure communications and defense against heat-seeking missiles.

"This development shows that despite popular belief, a laser can indeed be made on a silicon chip," said Bahram Jalali, professor of electrical engineering at the UCLA Henry Samueli School of Engineering and Applied Science, who led the research team.

"The lack of a silicon laser has been a major roadblock in the progress of silicon optoelectronics and photonics," said Jagdeep Shah, program manager of the Defense Advanced Research Projects Agency Microsystems Technology Office, which funded the research. "The demonstration of a Raman laser in silicon has the potential to lead to new military applications in communications and sensing." Shah is a fellow of the American Physical Society and the Optical Society of America.

"Demonstration of the silicon laser by UCLA researchers is a major breakthrough that can make optical wireless a reality," said Jamie Montgomery, CEO of Montgomery and Co., a California-based investment banking firm specializing in the technology sector. "This technology also has important applications in homeland security."

"Our approach uses the natural atomic vibrations of silicon to create or amplify light," Jalali said. "This is significant because no special impurity or complicated device structure is needed."

This approach, called the Raman effect, is used in optical fibers for light generation and amplification. Until the UCLA research began, it had not been considered for creating silicon optical devices, since several kilometers of fiber are required to make a useful device whereas the typical silicon chip is millimeters in size.

In the past, many researchers have attempted, without success, to create a silicon laser by introducing impurities in the material, or by using exotic and complex device structures. Even if successful, such processes render the device incompatible with standard silicon manufacturing technology. In addition, these techniques generate light only at fixed wavelengths, and often do not correspond to the optimum wavelength for most applications.

While silicon is the so-called "bread-and-butter" material of the electronic industry, said Jalali, a member of the California NanoSystems Institute, conventional wisdom contends that it cannot be used to generate light.

The UCLA researchers exploited several properties of silicon in order to successfully demonstrate their silicon laser device.

"Silicon is a crystal with a well-ordered atomic arrangement, compared to glass fiber for example, which is amorphous with a random atomic arrangement," Jalali said. "This results in a very strong Raman effect in silicon that can be exploited to create a laser on a chip."

Silicon also has a high refractive index (3.5), whereas glass has a low index (1.5), and the optical energy in silicon waveguides is tightly confined, resulting in high intensity, further enhancing the Raman effect.

According to the researchers, the silicon laser exhibits nearly ideal characteristics and is already producing pulsed radiation with a very high peak power of one watt. Pulsed operation is needed in many detection and communication systems.

"A key attribute of the new technology is that it can produce mid-infrared radiation without any cooling," Jalali said. "This is a drastic improvement over current technology, where antimonite-based material plus cryogenic conditions are required to achieve lasing."

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Frank
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Frank,
User Rank: Light Beer
12/5/2012 | 1:07:02 AM
re: UCLA Claims First Silicon Laser
Silicon optics switches by changing refractive index

By R. Colin Johnson
EE Times
October 27, 2004 (6:04 PM EDT)

PORTLAND, Ore. G Silicon circuits traditionally don't do optics. As anc"indirect bandgap" material G one in which the bottom of the conduction band is shifted with respect to the top of the valence band G energy released during electron recombination with a hole is converted primarily into phonons instead of the photons. The result is a "direct bandgap" material like gallium arsenide.

Cornell University researchers have demonstrated nanoscale techniques they say enabled the world's first silicon chip that switches optical wavelengths. The key is a ring-shaped nanoscale cavity whose resonant frequency depends on its refractive index, which can be optically switched by virtue of a second light beam controlling free-carrier dispersion.

According to Cornell University engineer Michal Lipson, the technique should eventually enable terahertz switching of signals on silicon chips with ultra-low power, high-modulation depth picosecond optical switches. They can be fabricated alongside conventional silicon circuitry. "Our photonic circuits are for carrying information, not for logic," said Lipson, principle investigator and an assistant professor at Cornell in its electrical and computer engineering department.

The first application is likey to be all-optical routers rather than not photonic circuitry, which could come later. The National Science Foundation is funding Lipson's quest for techniques to enable silicon to handle optics applications.
deauxfaux
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deauxfaux,
User Rank: Light Beer
12/5/2012 | 1:07:04 AM
re: UCLA Claims First Silicon Laser
Really cool stuff, but unfortunately, optically pumped and commercially irrelevant for the next 5-10 years

http://www.opticsexpress.org/v...
deauxfaux
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deauxfaux,
User Rank: Light Beer
12/5/2012 | 1:07:05 AM
re: UCLA Claims First Silicon Laser
Redface

I am going to check into the details to be 100% certain on this point, if anything different comes out of my investigation, I'll track you down on one of the boards and correct my post.
But I am 99% sure.

Yes....hypesmanship. Jalali was able to hype one other company into acquisition by Intel (Cognet, I think), so none of this seems surprising.

Deaux
redface
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redface,
User Rank: Light Beer
12/5/2012 | 1:07:05 AM
re: UCLA Claims First Silicon Laser
Deaufaux wrote:
"Where is the pump"
The answer: It ain't Silicon yet.

Thanks for the answer. So this is not really a "silicon laser". Rather, it is some kind of nonlinear optics done in silicon waveguides. It is really disturbing when people refuses to call a horse's ass a horse's ass...

I believe Intel is working on a similar device based on Raman amplification in silicon.

deauxfaux
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deauxfaux,
User Rank: Light Beer
12/5/2012 | 1:07:06 AM
re: UCLA Claims First Silicon Laser
It is a Raman laser.....the real question is

"Where is the pump"

The answer: It ain't Silicon yet
redface
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redface,
User Rank: Light Beer
12/5/2012 | 1:07:07 AM
re: UCLA Claims First Silicon Laser
This seems to be an impressive achievement if it can be made practical.

I would like to know what is the lasing mechanism. How does the laser get its gain? Is it based on electrical pumping of power, or does it depend on optical pumping (in which case it probably would not be considered a true "silicon laser").
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