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04 Jan 2005
Our pick of three hot technologies that are set to light up the year ahead - part 1.
The dream
Silicon "super-chips" that integrate electronic and optical circuitry in a monolithic design.
Current status
There is no doubt that 2004 represents a turning point in the development of silicon photonics. In February, Intel, the US computer-chip expert, demonstrated a high-speed (1 GHz) optical modulator made entirely from silicon.
Then, in November, scientists at the University of California, Los Angeles (UCLA), US, made the headlines when they demonstrated the world's first silicon laser - a silicon waveguide that uses the Raman effect and emits picosecond pulses at 1.68 µm. Ultimately, such devices could be integrated with electronics to create powerful "one chip solutions" for use in telecommunications and computing.
"If you open an optical module today, you will see two types of components in there. There is a laser, an amplifier, or a modulator chip that is made in GaAs or InP and then there are the electronic ICs that are silicon," Bahram Jalali of UCLA told Optics.org. "The first silicon photonic products will be single-chip, all-silicon versions of these products."
With key players such as Intel expressing interest, there are signs that industry is taking the technology seriously. Semiconductor specialist STMicroelectronics has recently demonstrated silicon LEDs that emit green light and plans to integrate them with silicon photodetectors to create an all-silicon optocouplers.
And this could be just the beginning. "Silicon is the ultimate manufacturing platform. Today, we can build over one billion transistors on a tiny chip, mass manufacture it, and sell it in consumer electronics at very low prices," said Jalali. "In the long term, one cannot help but dream of about an all-optical chip where both logic and communication is done optically."
Future challenges
Perhaps the biggest challenges facing silicon photonics are not technological but in fact related to market acceptance and demand. "The market size is still too small to justify integrated solutions," commented Jalali. "If the volume is low, the cost per chip will be high and no one will buy it. For silicon photonics to "fly", we need to see the market for optical products improve significantly."
Timeline
According to Jalali, it may only be a few years before the first silicon photonic devices start to hit the market. "I think that we will see breakthroughs in 2005 with commercial deployment starting to appear in 2007," he said. "Examples of these include optical modulators, amplifiers and Raman lasers with their driver and control circuitry integrated on the same chip."
Author
Oliver Graydon is editor of Optics.org and Opto & Laser Europe magazine.
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