Learning About Lasers

Let's say you're on the game show "Who Wants to be a Millionaire" and Regis (the guy who reads the questions) asks you the following question for one million dollars: What does the acronym LASER stand for?

A. Lampposts should Always be Seen on Every Road
B. Light Amplification by Stimulated Emission of Radiation
C. Laughing At Seals Exercising isn't Right
D. Liver And Sausages: Eat them Raw

If you don't know the answer, take whatever money you have and run. If B is your final answer, the check will be in the mail (wink, wink). If you picked A, C, or D, please read on and find out what Light Amplification by Stimulated Emission of Radiation is all about.

Lasers are used to read the information from compact discs.

According to Dr. Audra Bullock, an assistant professor and laser specialist at the University of Hawai`i, "a laser is formed when you take a material that normally would emit light and excite it by creating feedback with mirrors."

Lasers are everywhere and you may not realize it. In CD and DVD players, a laser is used to read the information stored on the disks. Laser printers use lasers to transform the computer-generated information into written words. Laser pointers that lecturers and public speakers use are actually miniature lasers, similar to those used in fiber optic communication systems. Police officers carry speed detectors, which use laser radar, otherwise known as LADAR (or sometimes called LIDAR-light detection and ranging). Lasers are also used for cutting and welding.

They also have medical purposes. One of the earliest medical uses was for surgery on the retina of the eye. However, one of the most common uses of lasers is probably the least known, "A lot of people don't realize that the grocery store scanners that read bar codes use lasers," Bullock said.

So what's the difference between lasers? "The color, amount of light, and the property of light," Bullock said. "Lasers used for surgery usually aren't continuous waves, which means they don't emit continuously. Instead, they emit a pulse, so little flashes of light come out."

"In the case of a laser pointer, it is just one continuous beam. The power for the pointer is in the milliwatt range, however a laser for surgery can use as much as several watts, producing a light that is a thousand times more intense than the beam from the pointer," Bullock said.

Perhaps one of the most exciting things about lasers is its use in fiber optic communications, which according to Dr. Bullock, will become big here in Hawai`i.

Fiber optic cables are made out of glass-like material that is stretched to the point where it becomes very small, long, and cylindrical. Since it is very small and long, the glass becomes flexible. Communication signals are sent on beams of light through these glass cables. "Fiber optic communication systems are useful, because you can run fiber optic cables like electrical lines and a fiber line has a very high data transmission rate." Bullock said.

Dr. Bullock and the Laser Communications Laboratory.

In the near future, a large fiber optic cable will be laid that will originate from Asia, run through Honolulu, and end up on the West Coast of the United States. The 5-terabyte cable will be one of the largest bundles of fiber optic cables in the world.

Despite the new cables, the majority of fiber optic research is focused on optimizing the fiber optic cables already laid. Dr. Bullock is involved in finding ways to maximize the data transmissions of fiber optics.

"When fiber optic cables were laid years ago, the fiber wasn't intended to handle today's capacity, so now we have to come up with ways to maximize the transition rates on them," Bullock said. "The initial intent was to send one signal on a dedicated fiber bundle. Now we're looking at ways to send hundreds of communication signals simultaneously across one fiber."

So how could fiber optics affect us all? Dr. Bullock believes that within the next decade you could see fiber optic cables connected to our homes. Fiber optics is a much faster option than cable and DSL modems.

However, Dr. Bullock says connecting fiber optics to homes will be very expensive, unless there is a great need for it. "I think the growth of computers and the Internet, especially data conferencing and all the other wonderful things we're doing on the web are going to give us the need for fiber optics."





 

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