Fiber optic cables for USB 3.0 interconnect

We all know that USB 3.0 is fast. It’s 5 Gbits/s (640 Mbytes/s) — over ten times as fast as the 2.0 maximum. Accounting for the encoding overhead, the raw data throughput is around 4 Gbit/s. But, USB 3.0 is limited to 3 meters. What if you need to go further?

There is a very straight forward, though not totally inexpensive, solution to that problem. It involves fiber cable with optical transceivers built right into the USB connectors.

One supplier of active optical cables (AOC) is Corning. Their 3.Optical brand cables come in lengths of 10, 15, 30, or 50 meters and have Type A connectors at both ends. They operate over 0° to 45°C and require no external power supply as they use USB power at both ends. The cables are also hot swappable.

A big advantage to their system is the small, very light, and very flexible optical fiber used. This cable has a “zero-bend” radius, is very easily bent to 180 degrees with no damage, and can withstand lots of bending, squeezing, and tangling without damage or loss of function.

One application area is machine vision. One of the challenges faced with installation of machine vision systems is the long runs of cables required to connect multiple cameras at various locations on the production line to a host system. The host system actively monitors the production flow and operates the automated levers, gates, and air jets that are used to maneuver the products being monitored. USB 3.Optical cables overcome this challenge by offering a very rugged, yet light cable that can handle long runs. The host systems demand very high speed, low latency communications and high-resolution imagery and use control signaling on the wire to make intelligent decisions.

Other applications include video communication, digital photography, digital signage, and point-of-sale. A 15 m cable is about $165 (AOC-ACS2CVA015M20). See http://goo.gl/wm7PcB.

Another USB active cable supplier is FOCI (Fiber Optic Communications, Inc.) of Taiwan. They  offer the L-SD-UA USB 3.0 and HDMI 1.4 active optical cable to break the USB 3 distance limitation, extending to 100 meters. Additional plug-and-play and hot swapping support enables the technology to benefit commercial and industrial applications such as digital signage, HD surveillance systems, and ultrathin client (where end user's computing device has no local storage), and digital home theatre. Their L-SD-UA cable supports all USB 3.0 device types: control, interrupt, bulk and isochronous at up to 5 Gbits/s using 3 mm 850 nm VCSEL (multimode) cable. See www.foci.com.tw/pd_sub1.html.

There are also fiber optic extender boxes available from a few sources, including Black Box, L-Com, and Icron.