It’s not easy being green

Green lasers appear to have been very visible (sorry!) in both the trade publications and general large-circulation newspapers recently.

Apr 1st, 2008
Th Jbairstow

By Jeff Bairstow

Green lasers appear to have been very visible (sorry!) in both the trade publications and general large-circulation newspapers recently. I admit I was rather puzzled by this phenomenon. Maybe this somewhat minor brouhaha was started by some underemployed industry spin doctors on a slow news day. So I Googled around the Internet with “green lasers.” There was plenty of coverage of the subject but it mostly revolved around one big media event, courtesy of the Pentagon. Ahah!

In fact, there was so much PR ballyhoo produced last November by DARPA’s announcements of substantial grants to nine research centers in the hope of developing a manufacturable high-power green laser based on gallium nitride (GaN) that even the august The Wall Street Journal devoted a column to this very same subject.

Please don’t get me wrong. Despite the more usual “gee-whiz” take by largely uninformed reporters, I’m generally very pleased to see the major news outlets taking a serious interest in our industry. We normally have a hard time in getting onto the front page or the TV six-o-clock news unless it’s some cockamamie tale of a youngster with a laser pointer dazzling the pilots in the cabin of a Boeing 747 coming in to land at New York’s JFK Airport.

But, as you may have read from time to time in these pages, the economic manufacturing of powerful, practical gallium nitride lasers isn’t easy, and, until recently, the U.S. has lagged big-time in this field. I guess this situation could change if the DARPA program achieves even a modest measure of success. The odds don’t look too good. But do we really need a handout from the Pentagon to manufacture GaN lasers?

The program, called VIGIL (Visible InGaN Injection Lasers) has a goal of building a semiconductor green laser offering one watt of continuous-wave output at 500 nm, within three years. Given that goal, the word “vigil” may be most appropriate for this project. There will be many vigils and “all-nighters” as researchers attempt to reduce the internal defects resulting from combining indium with gallium nitride.

As many semiconductor chemists and research engineers are only too well aware, the combination of a small amount of an impurity can drastically lower the yields of semiconductor wafers. Unlike the manufacture of large silicon wafers, the manufacturing of gallium nitride wafers is still much more of a black art than a clean science.

So why is the Pentagon’s DARPA funding this research and doing so mostly through already well-funded university research groups such as the Georgia Institute of Technology and the University of California at Santa Barbara? To be sure, all of the groups winning grants are already active in this field, many of them already receiving significant financial support from non-DARPA sources such as several leading laser and semiconductor manufacturers.

And just what does the Department of Defense expect to get out of this project? Well, ok, I can see some possibilities in head-up displays for fighter pilots. But, just an aside, when was the last time you heard of a fighter pilot engaging in a dogfight? Another suggestion by the Pentagon is underwater communications. But is it realistic to envisage underwater communications using green-laser emissions? I don’t think so. Even if these applications had some commercial possibilities, the likelihood of a nonmilitary market developing is slight.

As a taxpayer, do I want to see my tax dollars supporting research that could and should be funded from within the industry? As a former researcher, I can assure you that I do appreciate the very real difficulties of finding sufficient funds to keep a world-class team of researchers together and having sufficient money to buy the extremely expensive equipment that would permit them to do leading-edge research.

So, is all this hoohah about green lasers justified? Not in my view.

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Jeffrey Bairstow
Contributing Editor

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