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Evanescent Lasers to Speed Up Data Transmission
Roland Piquepaille writes "Researchers at UC Santa Barbara (UCSB) have built the world's first mode-locked silicon evanescent laser. But what is an 'evanescent' laser? It is a step toward 'combining lasers and other key optical components with the existing electronic capabilities in silicon.' In other words, this research work will provide a way to integrate optical and electronic functions on a single chip. As these evanescent lasers can produce stable short pulses of laser light, they will be useful for many optical applications, such as high-speed data transmission or highly accurate optical clocks."
A turtle. Turtles, all the way down, man.
What bothers me, though, isn't the lasers, it's that this is the second Roland story in less than 24 hours. That Roland must have some amazing oral skills.
It's not offtopic, dumbass. It's orthogonal.
According to TFA, the stimulated emission of light actually takes place in an indium phosphide (InP) laser diode. The laser diode is bonded to a silicon waveguide, which acts like a miniature optical fiber to guide the laser light around the chip. The "evanescence" is because the laser light is evanescently coupled from the laser diode into the waveguide. A proper description of evanescent coupling requires a pretty sophisticated understanding of electromagnetism, but the short version is that if you shine a laser beam parallel and adjacent (within a few microns) of a waveguide or optical fiber, some of the laser light will hop over and start propagating down the waveguide or fiber. In particular, by placing the actual laser parallel to and near a carefully-designed waveguide, you can have almost all of the laser light emitted into the waveguide, even though the constituent atoms of the waveguide are not emitting any light at all! For this reason, I think the name "silicon evanescent laser" is misleading since the silicon isn't emitting any light, and Roland Piquepaille's description of evanescent lasers is just flat out wrong. Getting silicon to emit light remains an extremely difficult task, and as far I know, no one has succeeded yet in getting silicon to convert electricity directly into laser light.
7 3. However, that paper doesn't really define the term "evanescent laser" anywhere, so I had to go back to one of the research group's earlier papers to find a decent description of an evanescent laser and understand the physics of the device.
If anyone wants to read the Optics Express paper referenced in TFA, it's available online at http://www.opticsexpress.org/abstract.cfm?id=1409
"It take 9 months to bear a child, no matter how many women you assign to the job."
We need a new negative mod category, "stupidly contrived use of a meme that was never funny to begin with".