Slashdot Mirror
Intel Researchers Build Laser on Chip
Victor Ramen writes "Working with the basic material of computer chips, Intel Corp. researchers have constructed an all-silicon laser that could lead to computers one day harnessing light waves rather than electrical currents to shuttle data swiftly. 'Once you have silicon as an optical material, then you can take advantage of this enormous (silicon) infrastructure that exists around the world,' said Mario Paniccia, director of Intel's photonics lab. 'You can imagine starting to siliconize photonic devices, and maybe integrate photonics and electronics.'"
Many fellow /.ers seem to wonder why this is newsworthy since integrated photonics is not something new. That's true. But the introduction of solid-state silicon-based lasers is nothing short of revolutionary.
The discussion and research, thus far, on integrated electronics has hit a road block. Electronics is a silicon-based techology; photonics, for the most (and better part) is not. Specifically, photonic devices, and in particular laser emitters, are made out of a group of materials known as III-V (called three-five) materials, in reference to their position in the corresponding tables of the periodic table (consider, for example, gallium-arsenide GaAs).
Silicon is not a III-V material. It belongs to column II of the periodic table (notice that columnnar position refers to atomic properties and not to the actual column of the table. For example, column III in the periodic table is spread over actual columns number 3 and 13).
The fact that silicon and III-V materials do not share common chemical and crystalline properties, as implied by their different positions on the periodic table, is detrimental. The mismatch in their crystalline structure makes the monolithic integration of tiny laser emitters on top of silicon chips, impossible.
Yet we all agree that optical interconnections between computer components are the key for electronic computers to become better and faster.
Since monolithinc integration of lasers and CPUs was impossible, till now, because of the materials' mismatch we had to resort to the following limited ways of engaging photonics in computing:
(a) use of photonics for long-haul data transfer, ie, optical interconnects between entire computers, aka, optical networks; they are great and fast but we still face the bottlenect at the points of conversion between optical and electronic signals.
(b) hybrid optoelectronic chips; consider a silicon chip with pads on which a GaAs photonic chip rests. The two chips exchange signals thru these pads. The drawback here is the rather poor yields in fabrication and the high cost due to limited demand (and applications) for such devices.
(c) all optical computers. This was sort of a chimera for many researchers (myself included). While the idea and the concept are promising the implementation is extremely difficult and the promise of quantum computers, now, makes optical data processing a thing of the past.
Ideally we want a CPU chip made of silicon capable of emitting and receiving light. The photonic component was very difficult on silicon. Silicon is not an ideal material for coherent light emision, neither does it detect light easily. You need a larger area to sense light on silicon, than on GaAs, making silicon photodetectors rather large and thus affecting the scale of integration.
What Intel appears to have done now, is to introduce a way to monolithically integrate laser sources on silicon chips. They have solved a problem that has been open for years. Their solution will catalyze a field that has been waiting years for such a breakthrough. We knew what to do but we did not have the technology to do it. Intel just gave us the technology we've been expecting.