Optics for Universal I/O and Speed

by George Lawton

Intel has demonstrated new technology, code-named Light Peak, for connecting PCs and other devices using fiber optic lines. The company expects the technology to find its way into a variety of consumer electronics devices such as printers, storage devices, TVs, and media players. Light Peak promises a universal connector that will support various existing protocols including USB, FireWire, Digital Video Interface (DVI), and High-Definition Multimedia Interface.

The first-generation technology supports data rates of 10 Gbits per second in both directions, which is significantly faster than USB 2.0 (480 Mbps), the proposed USB 3.0 (4.8 Gbps), FireWire (400 Mbps), and DVI (3.96 Gbps). Light Peak will be able to carry multiple protocols simultaneously, which would let a single fiber connect to a hub that can support video and ports for various external devices. The link will scale to 100 Gbps bidirectionally in the next decade, said Jason Ziller, director of Intel's Optical I/O Program Office. 

Building Market Momentum

Thus far, Sony is the only consumer electronics manufacturer to publicly support the technology. However, several optical component vendors have announced plans to make Light Peak components, including Foxconn, Foxlink, Avago, SAE, Iptronics, Corning, Elaser, and Ensphere. The first products are expected by fall of next year.

Intel is also working to finalize a standard, which Ziller expects will drive higher volumes and broader use. But the company is still exploring avenues for standardization. "We want to determine the best way to standardize this technology, but there are no concrete plans," Ziller said. Working with the IEEE is one possibility under consideration. Other approaches involve organizations such as PC-industry special interest groups.

Richard Doherty, research director of the Envisioneering Group technology assessment company, said optical makes sense for faster interconnects because traditional copper technologies can't cost-effectively scale up to faster speeds. "The optical industry as a whole has demonstrated the ability for fast lasers and sensors to handle these data rates," Doherty said, "and Intel has a lot of experience in silicon. The only missing link is having an optical interconnect that’s easy for consumers and businesses." He sees Light Peak reaching consumer scale quickly, leading to connectors that cost "pennies instead of dimes and dollars."

The practical speed and length limits for traditional copper interconnects arise from issues associated with electrical losses and electromagnetic interference (EMI). These issues don't affect optical technology. Light signals can travel long distances with minimal optical losses, and they're immune to EMI. High-end optical transceivers and fibers can carry terabits per second across thousands of miles. Light Peak will operate over much shorter ranges so it can use significantly cheaper components.

Making Fiber Consumer Friendly

The Light Peak technology consists of a controller chip and optical module that can be built into devices. Intel plans to supply the controller chip and is working with optics vendors to deliver the other components. 

Fiber-optic connectors are already widely used in high-end audio equipment with Toshiba-Link (Toslink) technology. Toslink operates at a wavelength of 655 nanometers. It originally supported a data rate of 3.1 Mbps and was later expanded to 125 Mbps. It uses an LED and has a range up to 10 meters over plastic fiber.

Light Peak uses a vertical-cavity, surface-emitting laser operating at 850 nm. It was designed to support a range up to 100 meters over glass fiber. This will extend the range of the different protocols it supports, which are limited to 3 to 15 meters over copper. Ziller said that vendors will likely include power on the cable, which might restrict the distance.

Intel balanced available technical alternatives to optimize for mainstream devices that ship in high volume. The technology had to be cost effective and durable enough to withstand consumer abuse. Glass fiber-optic cables are generally less durable than plastic, but Ziller said the Light Peak design works even when tied into knots or wrapped around a finger.

Doherty sees the possible early ramp-up of a high-speed wireless technology as the only real competition to Light Peak becoming a universal interconnect. New 60-GHz networking technology has this potential, but it hasn’t yet penetrated the consumer market. 

George Lawton is a freelance technology writer based in Monte Rio, California. Contact him at glawton@glawton.com.