Intel claims silicon laser revolution
A huge increase in speed for high-end computing applications could be on the cards after a US team announced that it had created the world's first electrically-pumped hybrid silicon laser.
In making the device, Intel and UC Santa Barbara researchers claim to have combined the light-emitting properties of InP with the manufacturability of silicon for the first time.
"This could bring low-cost, terabit-level optical data pipes inside future computers and help make possible a new era of high-performance computing applications," said Mario Paniccia, the director of Intel's Photonics Technology Lab.
In the hybrid structure, InP material generates and amplifies light to create the laser, while the silicon structure acts as a laser cavity and is used to route and control the emission. Light enters into the silicon through a physical effect known as evanescent coupling .
The initial laser made by Intel emits at 1.58 µm, although this wavelength can be adjusted by modifying the silicon waveguides used.
According to Intel, the key to making the device is the use of a low-temperature oxygen plasma. This creates a thin oxide layer on the surface of both materials.
When heated and pressed together, this oxide layer acts like a glue and fuses the two different materials into a single chip. Intel claims that unlike other methods that have been tried, this eliminates any problems due to lattice mismatch between the two materials.
UCSB's Jon Bowers says that this bonding method can be used at the die, partial-wafer or full-wafer level, and could become a solution for large-scale optical integration on a silicon platform.
Intel CTO Justin Rattner says that if the latest development can be scaled up for mass production, it ought to solve the cost issue with current photonic chip manufacturing. Presently, the cost of a laser chip for communications can be up to 100 times that of a silicon chip.
Infinera, the Sunnyvale, CA, company that has developed an integrated approach for current telecommunications applications, says that Intel s work is a "great endorsement" of the photonic integration concept.
However, it disagrees with Intel s conjecture that InP is an "exotic" material that is inherently expensive. Infinera believes that the cost of manufacturing devices is dictated more by the level of volume production required.
Intel and Infinera are both aiming to penetrate the computing market in the longer term as the photonics industry evolves, and both believe that this application area will provide the high component volumes needed to bring device cost down.
Intel has previously claimed silicon photonics breakthroughs, such as last year's optically-excited Raman laser. However, this latest research is the first to detail a chip that can be powered electrically.
The company says that its vision is to build chips containing hundreds of hybrid silicon lasers using established high-volume, low-cost manufacturing methods.
Intel is one of a number of companies seeking the "holy grail" of a silicon photonics. US-based start-up Luxtera has pursued a similar approach to Intel by using both silicon and InP material (see related feature article).
