The audio-production suite I use exploits, among other things, 48 channels of audio signaling that routes through six strands of POF (plastic optical fiber). Six strands of POF that take the place of 192 individual wires and shields. And when I say takes the place of that’s a bit of an exaggeration: The six POF strands occupy less than 10% of the space that the signal-carrying equivalent of copper cabling require. POF’s benefits with respect to volume, weight, and routing flexibility came to mind over the weekend as I reconfigured the production suite for a CD-mixing session that began today. Of course, POF’s advantages don’t end with its mechanical attributes and signal-carrying capabilities.

Optical interconnects also exhibit performance superior to copper with regard to RFI susceptibility and emissions, ESD robustness, channel-to-channel crosstalk, and galvanic isolation—four issues that every designer of copper-connected signal-processing systems must consider no matter if the signals in question reside in the analog domain or are encoded as bit streams. Additionally, in multi-channel applications, POF cable assemblies cost the same or slightly less than their copper equivalents. Yet, surprisingly, we don’t see POF penetrating the interconnect market to the extent that its benefits might suggest.

To date, EIAJ optical links—better known as TOSLINK—appears to be the most successful form of POF. Introduced by Toshiba more than 25 years ago, TOSLINK most commonly conveys SPDIF-encoded signal pairs—a data payload of about 1.4 Mb/s. TOSLINK connectors are common on home entertainment, semi-professional, and professional equipment. Alas, most often, you’ll find TOSLINK ports with their dust covers in their factory-installed positions.

Starting nearly 20 years ago, Alesis adapted TOSLINK photonic interfaces and POF media for their proprietary signaling system known as Alesis Lightpipe, which carries data payloads of about 9.2 Mb/s and which has since been widely adopted by numerous audio-equipment OEMs. Yet, in the ensuing two decades, the market has enjoyed little further improvement. Alesis lightpipe is still in use and apparently still delivers the same data payload.

In 2006, Fujifilm announced their Lumistar-X GI (graded-index) POF and 850 nm VCSEL-based (vertical-cavity surface-emitting laser diode) photonic transmitters capable of 10 Gbps data rates. Though the Fuji GI POF’s signaling bandwidth is plenty adequate for the application, the fiber-optic version of HDMI uses multi-mode glass fiber stock. The shortest assemblies I’ve found are 30 m—covering applications requiring run lengths that exceed the reach of copper-based HDMI. Short fiber-optic HDMI interconnects cost several hundred dollars, which puts them beyond the budgets of most consumers.

Depending on the specific format, HDTV requires 1 to 3 Gbps data rates—a bit more than two-orders-of-magnitude greater than current applications for the inexpensive Alesis lightpipe technology demand but well within demonstrated GI POF capabilities. Yet, with rare exception, consumer media interconnections use copper interconnects. Media-production facilities use a mix of copper and glass fiber. Can POF gain market traction in these segments? What do you see as the requisite cost and performance targets for POF interconnects in consumer media applications? What other signaling applications can you envision benefitting from POF’s capabilities? Post your comments.