CONNECTING THE COMPOUND SEMICONDUCTOR COMMUNITY
July 2010 Volume 16 Number 5
Editor-in-Chief David Ridsdale
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Consultant Editor Richard Stevenson PhD
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dh@angelbcl.co.uk
I wrongly assumed that Sumitomo’s unveiling of its semi-polar 531 nm laser last summer had answered the question over which plane to grown green lasers on. But Osram’s efforts have well and truly muddied these waters.
What is for sure is that the future will settle this debate. Semi-polar lasers are still a relatively immature technology, and how much more performance can be squeezed out of them is not yet clear. But having said that, if you rewind the clock a few years, it seemed that after a decade or more of development, conventional nitride lasers were hitting a wall at 490 nm. With the benefit of hindsight, however, we know that this class of laser could do far better.
Another big question concerns the commercial viability of the various classes of nitride laser. For example, very little has been published on the reliability of semi-polar lasers.
There is also the issue of cost. Conventional gallium nitride substrates are dear, but they are still far cheaper than semi-polar GaN. Substrate prices are not the only issue, however. Yields will play a major role, and today’s R&D efforts have only hinted at what is possible in this regard.
What is for sure is that it will be fascinating to witness the commercial development of green lasers. Whether Osram will be the first to triumph is anyone’s guess, as Sumitomo, Nichia, and Kaai will also be busting a gut to get their products to market first. It promises to be a great battle.
Richard Stevenson PhD Consultant Editor
js@angelbcl.co.uk mg@angelbcl.co.uk
My shock was two-fold. Firstly, the power output is incredibly high - the only other reports north of 520 nm that I am aware of have been for devices delivering just a handful of milliwatts. And secondly, the German outfit had built its device on the polar plane of gallium nitride, a cut that has been widely touted as inappropriate for long wavelength nitride lasers.
sc@angelbcl.co.uk E:
tbrun@brunmedia.com
Peruse through the journals and you’ll find plenty of papers detailing incremental, but undeniably important breakthroughs. Just occasionally, however, sitting among them you’ll also find a gem that makes you sit up and think wow, that really is impressive.
I recently experienced that rare and joyful moment when I spotted Osram’s paper announcing a 50 mW, continuous-wave laser emitting at 524 nm.
sm@angelbcl.co.uk tb@angelbcl.co.uk
Osram’s great green laser
jc@angelbcl.co.uk dr@angelbcl.co.uk
editorialview
July 2010
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