Light Peak + USB 3.0 = Awesome!

Yesterday I talked about Light Peak, the new optical interconnect being developed by Apple, Intel, and others. Today I’m continuing that theme, suggesting a possible productization that would really take Light Peak to the next level: Integrating it with USB 3.0.

Light Peak Background

As discussed yesterday, Light Peak is a cable, not a protocol. It’s a mechanism to carry data from one point to another at high speed but lacks a schema for that data. Instead, Light Peak will carry existing data types like USB, DVI/HDMI video, Ethernet, and perhaps even PCI.

But one major element is lacking at this point: Power. Most existing interconnects carry data as well as low-voltage DC to power connected devices. USB is the poster child, with many USB devices powered by the port rather than an external “power brick”, but other interconnects feature power as well: Power over Ethernet is in wide corporate use, especially for voice-over-IP (VoIP) telephone systems, and the HDMI includes DC power as well, though just 5 volts and 50 mA.

Being an optical medium, Light Peak cannot easily carry power, since the plastic fibers used are non-conductive. Although Apple and Intel have hinted at a bundled copper wire for electrical power, one thin and flexible enough would experience an unacceptable voltage drop over the long runs possible with optical fiber. Therefore, we are likely to see a number of permutations of Light Peak:

1. Native optical-only Light Peak for long distances or devices not needing power
2. Light Peak bundled with a power cable, as hinted in this Apple patent
3. Light Peak bundled with a data cable, likely USB

It is this last permutation that interests me the most.

How Light Peak Will Be Used

Imagine a new MacBook Air with a single I/O port. Unlike the old one (which used slow USB 2.0), this new device could connect at high speed to just about anything through a simple converter or docking station. And images suggest daisy-chained devices reminiscent of today’s rarely-used FireWire connection.

It seems very likely that the eventual Light Peak products will carry USB, DVI or DisplayPort, SATA, and Ethernet data over a single cable. Since it has so much bandwidth, Light Peak will probably support both conventional and higher-speed variants of those protocols: This means that USB 2.0 and 3.0 will coexist, as will 1.5, 3, and 6 Gbps SATA and Gigabit Ethernet. We will probably even see PCI Express extended over Light Peak!

Apple has long championed thinner form factors and reduced cable clutter, and it’s worth noting that they’re the driving force behind Light Peak. This makes the concept of a single-port MacBook that much more likely. But what will that port look like?

Light Peak = USB 3.0?

Despite the over-used graphics representing a surface-mount 4-fiber Light Peak connector, the end-user plug-and-cable form factor hasn’t been decided. One serious drawback of optical connections is that they can’t transmit power, putting a crimp in the “one wire” vision. So the safe money says that final Light Peak spec will include both copper (for power and perhaps additional data) as well as optical channels bonded together into a single cable.

I’m going to go out on a limb and suggest that a common variant of Light Peak will in fact use a fully-functional USB 3.0 port with one or two optical connections embedded in the center. Just as the headphone jack used in many Macintosh computers today includes a Mini-TOSLINK optical cable in the center, these Light Peak-enabled USB connectors will be compatible with current USB devices, from thumb drives to coffee warmers.

But connect a Light Peak-capable device (using a plain-looking but optical-enabled USB-type cable) and a whole new world will open up. The copper wires will carry an amp or two of power, allowing a monitor, hard disk drive, or printer to come to life, and these will include additional Light Peak ports for more device connectivity. I imagine we will see Light Peak USB hubs contained in monitors which will act as a docking station to this future MacBook.

One issue for this USB-centric vision is the connector itself. Being an optical media using extremely thin fibers, Light Peak connections will need precise mating of connector and jack. But conventional USB is much more tolerant of misalignment, and this connector might be unsuitable for optical usage. The slimmer mini USB variant used by some USB 3.0 devices is more appropriate for this use, but this may not be an issue after all: Intel’s videos show what appears to be a conventional USB plug carrying Light Peak already!

Stephen’s Stance

But What If Light Peak Was Electrical Rather Than Optical?

My theory is simple: Light Peak will be a superior and enhanced version of USB 3.0 rather than a competitor or replacement. Apple is holding off on the USB upgrade so they can deliver this new world, not so they can scuttle it. They have learned the lesson of compatibility but want a superior one-wire experience for users. They’ve even delivered a prototype with the optical-capable audio jacks found on every current Macintosh computer!

I expect to see such devices hit the market in late 2011, and hope this backwards/forwards compatibility vision is realized. Without the USB/Light Peak connection, we could be witnessing FireWire and DisplayPort all over again, with Light Peak pushed aside as a proprietary Apple-only connection for high-end devices. A combination of Light Peak and USB is an ideal way to prevent this kind of marginalization!