Replacing Mirrors with Photonic Crystals to Shrink On-Chip LasersCategory: Science & Technology
Posted: July 25, 2012 08:32AM
Electronic communication is coming up against a wall when it comes to speed. As fast as electricity is, so much data has to be moved so quickly that electrons on copper wire just will not cut it soon. For some time fiber-optics have been employed to take advantage of the speed of light, but only for large-scale networks because the technology needed to produce and receive the light signals is difficult to make small. Now researchers at University of Wisconsin, Madison and University of Texas at Arlington have found a way to shrink the laser light source down to something that can fit on a computer chip.
Chip-scale lasers have been made before, but normally they are 20-30 microns tall which can dwarf the silicon around them. This is unacceptable to the researchers, so they set out to improve this and found an interesting way to do it. Lasers often require mirrors to operate, and the classic mirror can only be so small. The researchers decided to replace the mirror with a photonic crystal and found that just one crystal is equivalent to 15-30 layers of mirrors. This will allow the lasers to be made just 2 microns tall, which is more in line with the silicon circuitry around it.
Another benefit to using the photonic crystals this way is how they are added to the chip. Unlike the traditional lasers which require high heat, this design can be applied using a nanomembrane transfer printing process. This is far more compatible with the manufacturing of silicon computer chips which could be damaged by the heat to apply the original lasers.