BYU electrical engineers use light to beam music

Published: Thursday, Dec. 22 2011 1:40 p.m. MST

The free space optical transmission device, an electrical engineering laser music project, on Dec. 19, 2011.

Mark A. Philbrick, BYU

PROVO — Using a laser to beam music from one place to another? It’s not science fiction, it’s a reality thanks to some BYU electrical engineering students.

The system is called a free space optical transmission device.

"We have our music coming in from an iPod, or some other music device, and then it comes in, converts it to digital and then sends it across this laser to our receiver and that converts it back so you can listen to it on your speakers," said Matt Seamons, a student who worked on the project.

But it's not just about making music more mobile. There are potential real world applications beyond just the convenience wireless portability.

Encrypted military communications are broadcast everywhere when they use electromagnetic waves, making them available to anyone who wants to do the work of breaking the code.

"This actually has a very narrow beam width, so when they are transferring the information ... it's not as easy to tap into," Seamons

There are other possibilities as well. One can easily imagine using a system of these lasers to connect government offices, businesses or any other party that needs no prying eyes.

"It's very secure," said Jana Sardoni, whose work focused on putting the device together.

To tap into the beam means to break the signal on the other end, meaning that the receiver would instantly know something was getting in the way — not to mention trying to focus the beam and encrypt the message.

Basically, the system works because the laser gets brighter or dimmer based on the current sent into it. The faster the user can get the beam to change, the more information the user can transmit.

"All information is ones and zeros. When the light gets brighter or dimmer, it's either a one or a zero," Sardoni said.

Right now they're at about 5 megabits per second. The team hopes to get to the point where beaming video files becomes a possibility.

This laser device is a continuing project and during each subsequent class, the students try to improve on the design in some way. This year, the team focused on battery life. 

In fact, the laser transmitter didn't have batteries at all before and needed to be plugged in. Now, the team can get a few hours of transfer time out of just a few AA batteries.

This limited the researchers' ability to transmit to a distance of about 35 feet. But with enough power and proper power management, they think they could get all the way out to a satellite or a space station.

Still, the tradeoff is worth it, since it allows the system to be fully portable, ready for demos, and usable in a much wider range of areas.

These students were almost entirely on their own in the class project, guided only by their teacher and the knowledge they had gained during their earlier classes. 

“Seeing everything come together at the end, working even better than we expected, was really cool,” said Sardoni, who has already accepted a job offer from Intel to design processors.

There was not even a textbook involved.

"It's very flexible. It's fun. It's a lot more enjoyable than your average class," Sardoni said.

And who knows? It's possible this might even replace the need for cumbersome wires in home speaker systems. 

"I hope so," she said. "I hate having to deal with all the wires going from the system to the speakers. That would be a cool thing to do."

Contributing: Randall Jeppesen

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