Most people have already read many stories about holographic storage and discs containing more than 2 layers promising that would bring us ultra storage high capacities on a CD sized disc, however this has not stopped research into improving the capacity of single layer media. Just when Blu-ray appeared to offer the feasible limit per layer due to the difficulty in focusing laser light to narrower spots without moving further to more expensive shorter wave length lasers, researchers at Kyoto University have developed a new laser that can produce a beam of down to 1/10th the size of that produced by existing laser modules of the same wavelength.
The new
semiconductor laser technology uses layers of phototonic crystals incorporated on 0.5mm² semiconductor chips. These crystals contain 10,000's of tiny holes, each acting as a mirror, which cause light to resonate in the chip until it gets emitted as laser light, but with an overal beam diameter of up to 10 times smaller than that from semiconductor lasers currently available.
As the
beam can also be focused down to a tiny point 1/10th the size of that with a conventional laser of the same wave length (laser colour), it is possible to gain a 10 fold capacity increase on media using the same wavelength. By sticking with the same wavelength means that it is also possible to use existing blue laser disc technology with these new lasers to develop drives and media with capacities of up to 10 times that of Blu-ray without worrying about dealing with shorter laser wavelengths. Thanks to D4rk0n3 for reporting this news:
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The Kyoto University group, led by professor Susumu Noda, worked with Kyoto-based Rohm Co., Ltd. and the Japan Science and Technology Agency (JST) to engineer layers of photonic crystals consisting of tens of thousands of small holes, which were incorporated into 0.5 mm x 0.5 mm semiconductor chips. The photonic crystal layer works as an optical resonator, with each individual hole functioning as a tiny mirror that causes the light to resonate in the semiconductor until it is emitted as laser light. The result is a laser beam with a diameter up to 10 times smaller and with properties different from those of conventional semiconductor lasers. Futher details and technical info can be found on this news source. |
Until a time comes when dual layer discs or discs
containing more layers can be produced relatively cheap without costing multiple times that of single layer media, chances are that single layer media will remain the most popular for the foreseeable future, even with the next generations of optical discs. With the amount of research and development already put into Blu-ray and HD DVD, these will also likely be the leader in disc capacity for the consumer market for several years to come, even if other formats such as Holographic discs or other ultra high capacity discs using multiple layers finally hit the market in the meantime.
Source: Pink Tentacle
