The importance of optoelectronics

June 1, 2003
The long-anticipated optoelectronics revolution in military and aerospace applications is perennially five years down the road — no matter what year it is.

By John Keller, chief editor
Military & Aerospace Electronics

The long-anticipated optoelectronics revolution in military and aerospace applications is perennially five years down the road — no matter what year it is.

Granted, the promises that widespread optoelectronics offer for military and aerospace systems — decreased size and weight, vastly increased data processing and throughput, and broad resistance to electromagnetic interference — causes deep excitement and anticipation, yet these promises always seem to be just around the next bend.

Many of us have read about this utopian all-optical future, where all computer interconnects will be blindingly fast, where optical fiber and lasers and will take the place of wires and radio frequency (RF) data links, where inadvertent electronic emissions that the wrong people might intercept by will be things of the past, and where packaging problems such as metal migration will be rendered obsolete.

Obviously such a vision will be a long time coming, and as a result, a good deal of frustration and skepticism surrounds optoelectronics technology — particularly where military and aerospace uses are concerned. You can only promise great things without delivering for so long before people quit paying close attention and start sloughing-off the promises as empty rhetoric. We've all heard folks snort and say, "Yeah, yeah. I'll believe it when I see it."

People involved with technology have a low tolerance for now-familiar promises that have a lot more to do with wishful thinking than they do with reality. They have seen it before — too many times.

Remember artificial intelligence, popularly known as AI? This branch of what was to be leap-ahead technology was in vogue back in the mid 1980s. It involved rule- and knowledge-based expert systems, specialized and pricey Symbolics workstations, programming in the arcane List Processing Language — otherwise known as LISP — and the then-future promise of multiprocessor computer architectures called artificial neural networks that were to mimic how the human brain processes information.

If you don't remember this, don't feel bad; lots of other folks don't remember it either. The AI revolution never happened because much of it was a bunch of over-hyped promises. Still, AI research did not represent a completely wasted effort. Computer scientists learned a lot from their AI work, and much of what they came up with then is in use today, except that today it's not known as artificial intelligence, but simply as conventional processing.

In a similar way, the bright promises of optoelectronics might blind us to real progress in this technology, which as it turns out is far more incremental than it is revolutionary, and is likely to stay that way. One truism still applies, as it always has: if it sounds too good to believe, it probably is.

The promises of an all-optical revolution in military and aerospace technology can make us over-compartmentalize advanced technologies into optics and electronics, and consider these approaches as wholly separate technologies. Simply because optical technologies offer such a bright future, doesn't mean that systems designers should ignore electronic technologies. On the other hand, simply because the much of the so-called "optoelectronics revolution" of the future may be empty hype, doesn't mean that designers should ignore optical technologies.

It is for precisely these reasons today that optics and electronics are closer, perhaps, than they have ever been before. In fact, they have been, and continue to be, melding into a new discipline that combines the best of both technologies. Hence the need for such a hybrid term as "optoelectronics."

Fortunately, optical technologies often are strong in areas where electronics are weak, while electronics has plenty of advantages over optical technologies in certain applications.

For example, RF signals are great for sending voice and data easily over vast open spaces. Cellular telephones today make the most of RF signals by rapidly moving between over-air and over-wire data links. Yet where it makes sense, cellular phone networks also are using fiber-optic links to get the most performance from their systems.

Over-air RF links, however, tend to break down in confined spaces such as in buildings, tunnels, or aboard seagoing vessels. In such areas, RF signals bounce around, are absorbed, and often cannot reach their intended receivers.

In applications like this, optical technology is set to come to the rescue. Bolstered by companies such as Fiber-Span LLC of Piscataway, N.J., communications network designers in confined spaces today have the option of distributing small optical repeaters and fiber-optic networks throughout shipboard spaces, building floors, or in tunnels.

Mobile radio users can take advantage of this by sending RF energy to these repeater stations by line of sight. The repeaters then convert the RF energy to optical energy — without the need to digitize the signals — distribute the signals over the optical network, convert the signals back to RF, and retransmit to other areas behind walls, beyond curves, or to other areas where the RF-only energy might not be able to reach.

This is only one of countless examples of optical and electronics technologies blending into a new and fast-changing design discipline, which offers systems integrators a vast variety of design options to make the most of their systems.

At Military & Aerospace Electronics magazine, we plan to sharpen our view of evolving optoelectronics technologies and how they relate to military, space, and commercial aviation applications. It's clear that this is a vital road to the future. In our view of the progress of optoelectronics, we are not necessarily looking for technological revolutions. As always, we are simply on the lookout for technological solutions.

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