Beyond Blue

Ultraviolet lasers and LEDs made from zinc oxide are on their way

4 min read

High-definition DVD movies and players based on blue lasers have only just arrived on the market, but already a new generation is in sight, promising another fivefold increase in storage density. First-generation discs relying on red lasers could store about 5 gigabytes of data, and blue lasers have taken that to 50 GB. But if disc-player laser wavelengths could be pushed down into the ultraviolet part of the spectrum, disc densities could be hiked up to as much as 250 GB.

Brilliantly white light-emitting diodes also could be made from UV devices, accelerating replacement of inefficient ­incandescent lightbulbs and dull compact fluorescents by LEDs. A practical deep-ultraviolet LED would be especially valuable because ”if you have UV, you can excite anything in the visible,” says David Look, director of the semiconductor research center at Wright State University, in Dayton, Ohio. ”You could have pure red, blue, and green phosphors. Then you excite them in any proportion to get any color.”

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Deep Learning Could Bring the Concert Experience Home

The century-old quest for truly realistic sound production is finally paying off

12 min read
Image containing multiple aspects such as instruments and left and right open hands.
Stuart Bradford

Now that recorded sound has become ubiquitous, we hardly think about it. From our smartphones, smart speakers, TVs, radios, disc players, and car sound systems, it’s an enduring and enjoyable presence in our lives. In 2017, a survey by the polling firm Nielsen suggested that some 90 percent of the U.S. population listens to music regularly and that, on average, they do so 32 hours per week.

Behind this free-flowing pleasure are enormous industries applying technology to the long-standing goal of reproducing sound with the greatest possible realism. From Edison’s phonograph and the horn speakers of the 1880s, successive generations of engineers in pursuit of this ideal invented and exploited countless technologies: triode vacuum tubes, dynamic loudspeakers, magnetic phonograph cartridges, solid-state amplifier circuits in scores of different topologies, electrostatic speakers, optical discs, stereo, and surround sound. And over the past five decades, digital technologies, like audio compression and streaming, have transformed the music industry.

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