Silicon-based rainbow lasers transmit at 40 Gb/s

Posted by Rick C. Hodgin

Indianapolis (IN) - Researchers at the University of California in Santa Barbara last year were able to create a silicon-based laser capable of emitting 4 ps (picoseconds) light pulses.  This remarkable achievement broke past the silicon/laser barrier which had plagued scientists for decades. Its invention now also paves the way for electrically controlled silicon communication devices operating at speeds of about 40 Gb/s.

Electrically pumped "rainbow lasers" are comprised of several individual laser emitters spanning the EM spectrum.  Each one is independently coupled to its own silicon source and is, therefore, able to transmit and receive unique signals.  This configuration is desirable as optical transmissions are not subject to EM interference and, due to the properties of multi-spectrum light, a single fiber optics cable can carry many signals at the same time.  When it's all put together, this new technology allows single-component devices to be created and put into service where once massive stores of electrical components resided.  And, this new technology is more accurate and flexible because of its high speed and medium.

Researchers have achieved impressively low jitter signals which are differentiable at levels above 18 dB.  This high signal ratio makes the potential range of applications very wide, including even clock signaling.  It also represents a very fast turnaround from initial technology discovery (just last year) to a near-product form of the technology this year.  This speaks very highly of just how well understood the physics of this process are known today.

These kinds of optical lasers will eventually serve in products like high-speed data communications (even over long distances with repeater technology), remote sensing LIDAR systems and highly accurate optical clocks.  Potential uses in computers could include extremely high data exchange between server motherboards in rack or blade systems, as well as inter-component communications within a single machine.  It has been the desire of computer theorists for a long time to see the creation of an optical network within the machine.  These are all desirable uses for this new technology as there are properties of light which could solve several of the problems facing chip designers today, not the least of which is heat generation.