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MIT Researchers Make Advance Toward Photonic Circuits
MrSeb writes with this excerpt from an article in Extreme Tech: "Light-emitting diodes are a cornerstone of consumer tech. They make thin-and-light TVs and smartphones possible, provide efficient household, handheld, and automobile illumination, and, of course, without LEDs your router would not have blinkenlights. Thanks to some engineers from MIT, though, a new diode looks set to steal the humble LED's thunder. Dubbed a diode for light, and crafted using standard silicon chip fabrication techniques, this is a key discovery that will pave the path to photonic (as opposed to electronic) pathways on computer chips and circuit boards. The diode for light — which is made from a thin layer of garnet — is transparent in one direction, but opaque in the other. Garnet is usually hard to deposit on a silicon wafer, but the MIT researchers found a way to do it."
The summary (taken from the first article) implies that these new diodes are going to supersede LEDs, but they have completely different purposes. LEDs make lights, these things don't.
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The whole system could be made using standard microchip manufacturing machinery, Ross says. “It simplifies making an all-optical chip,” she says. The design of the circuit can be produced “just like an integrated-circuit person can design a whole microprocessor. Now, you can do an integrated optical circuit.” That could make it much easier to commercialize than a system based on different materials, Ross says. “A silicon platform is what you want to use,” she says, because “there’s a huge infrastructure for silicon processing. Everyone knows how to process silicon. That means they can set about developing the chip without having to worry about new fabrication techniques.”
It is good to see someone is coming up with an innovation that can "actually" be introduced. Seems like I read about new innovations every day on slashdot that never get off the ground because completely new manufacturing processes need to be created. Hopefully this will actually make it because it requires fewer changes by manufacturers (which can be significant barriers to innovation).
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Does this mean a light transistor is coming soon?
I am wondering if there is any material that acts as a mirror and can be switched from reflective to transparent electronically? I assume there is not or you wouldn't have devices like MEMS displays. I'm thinking if you had such a material it would be essentially a light transistor.
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It doesn't go off and start talking about LEDs and WDM which just confuses the issue.
http://www.mit.edu/newsoffice/2011/optical-computing-diode-1123.html
Well, much of the leaking in traditional electronic transistors is due to quantum mechanical effects, which would still apply to photonic devices. (With differences arising from such things as spin.) Some people are using evanescent fields from thin fibre lines to actually couple the signals in the line to other devices.
This article is just a rewording of the original article: http://www.mit.edu/newsoffice/2011/optical-computing-diode-1123.html
Fortunately, the kids at ExtremeTech were good enough to at least link the original which isn't nearly as confusing.
It's not a Light Emitting Diode, it's basically a Light Diode. Light can only pass through in one direction. The way this is normally done is by rotating the polarization of light through two polarizers. Any light of the wrong polarization cannot return back to the light source. This is usually used to protect laser sources and their modulators from return loss reflections in fiber optic systems that make use of polarization maintaining fibers.
Anyway, a 'true' optical transistor can be fashioned out of this if coupled with an optically controlled gain medium. If you have optical transistors, you can create optical NOR or NAND gates, and all basic logic functions can be created solely from these gates.
Just skimming the actual Nature paper itself, it appears they've basically created an optical isolator on a planar optical waveguide circuit.
To answer your last question: no.
You'd be better off with black construction paper for that.
This mentality is a big part of our national decline. Nobody wants to make the investments or do the hard work. They just want to swoop in when the technology is ripe for commercialization and reap all the profit from others' years of investment. Individuals and big companies act this out in different ways, but it boils down to, "just wake me up when I can get it on sale at Walmart."