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Published: September 26, 2006
Laser is an acronym for "Light Amplification by the Stimulated Emission of Radiation." The history of the laser dates back almost 100 years ago. The first person to work on the subject was Albert Einstein. In 1917, Einstein theorized the process of "Stimulated Emission." This was the first step in a long process of laser theory into everyday use.
Then, in 1954, the MASER (Microwave Amplification by Stimulated Emission of Radiation) was invented by Charles Townes. Townes used ammonia gas and microwave radiation. It is close to LASER technology but it does not use visible light.
Theodore Maiman then invented the Ruby Laser and Gordon Gould coined the term LASER. The gas laser was invented by Ali Javan in 1960 followed in 1962 by Robert Hall's revolutionary Semiconductor Injection Laser. This laser is still used in communications devices and electrical appliances today.
Without getting into the scientific gook that could cure an insomniac, lets talk about the essentials of Semiconductor Lasers.
A semiconductor laser is also known as a diode laser. In the basic rules of science, some materials conduct electricity better than others. Metals conduct electricity better than rubber, styrofoam, and plastic. Yet some materials fall into an in between category in which their electrical conductivity varies. These varying electrical conductors are called "semiconductors." The definition is "a solid-state device that consists of two outer semiconductor layers separated by a middle layer and generates laser radiation when charge carriers of opposite polarity, one each from the top and bottom layers, meet in the middle layer."
A good example of a semiconductor laser is to compare it to a sandwich. On the top layer is a sheet of metal, below that is a layer of P-type material. The active layer is below that, followed by N-type material, then the bottom layer of metal. The P-type and N-type regions produce a P-N junction, more commonly known as a diode. Both N-type and P-type semiconductors are formed in very close contact. The junction is the place where the two types meet. Both P- and N- types are conductive to electricity. However, when they are combined or meet in their junction, they are nonconductive. This is called the Depletion Zone.
In October of 2000 the Research and Development team at Bell Labs in Murray Hill, New Jersey experienced a breakthrough in laser development. Their research team developed a semiconductor laser that emits light in the far sides of the infrared spectrum. This region is both invisible to the naked eye and is difficult area to get lasers to work. The "world's longest wavelength semiconductor laser" is useful in detecting chemicals and pollutants in the smallest amounts. Pollutants in both the stratosphere and on Earth can be analysed by spectroscopes. Because gasses pass through laser light selectively, the analysis by chemists is similar to fingerprints collected by detectives.
Besides the highly scientific applications involving chemical analysis, semiconductor lasers have more practical applications, such as in laser printers for computers as well as in compact disc players.
Answers.com. "Semiconductor Laser," "Laser Diode." Copyright 2006. Answers Corporation. September 25, 2006. http://www.answers.com/topic/laser-diode
Riordan, Michael and Lillian Hoddeson; Feynman. "Semiconductors." Copyright 1999. ScienCentral, Inc., American Institute of Physics. PBS.org. September 25, 2006. http://www.pbs.org/transistor/science/events/semic s.html
Wikipedia. "P-N Junction." Wikimedia Foundation, Inc. September 9, 2006. September 25, 2006. http://en.wikipedia.org/wiki/P-n_junction
Bellis, Mary. "History of Lasers." About, Inc. Copyright 2006. New York Times Company. September 25, 2006. http://inventors.about.com/od/lstartinventions/a/l aser.htm
Press release. "Bell Labs researchers build world's longest wavelength semiconductor laser." Lucent Technologies. October 18, 2000. Copyright 2006. Lucent Technologies. September 25, 2006. http://www.lucent.com/press/1000/001018.bla.html
Weschler, Matthew. "How Lasers Work." How Stuff Works. Copyright 2006. HowStuffWorks, Inc. HSW Media Network. September 25, 2006. http://science.howstuffworks.com/laser7.htm
Theodore Maiman then invented the Ruby Laser and Gordon Gould coined the term LASER. The gas laser was invented by Ali Javan in 1960 followed in 1962 by Robert Hall's revolutionary Semiconductor Injection Laser. This laser is still used in communications devices and electrical appliances today.
Without getting into the scientific gook that could cure an insomniac, lets talk about the essentials of Semiconductor Lasers.
A semiconductor laser is also known as a diode laser. In the basic rules of science, some materials conduct electricity better than others. Metals conduct electricity better than rubber, styrofoam, and plastic. Yet some materials fall into an in between category in which their electrical conductivity varies. These varying electrical conductors are called "semiconductors." The definition is "a solid-state device that consists of two outer semiconductor layers separated by a middle layer and generates laser radiation when charge carriers of opposite polarity, one each from the top and bottom layers, meet in the middle layer."
A good example of a semiconductor laser is to compare it to a sandwich. On the top layer is a sheet of metal, below that is a layer of P-type material. The active layer is below that, followed by N-type material, then the bottom layer of metal. The P-type and N-type regions produce a P-N junction, more commonly known as a diode. Both N-type and P-type semiconductors are formed in very close contact. The junction is the place where the two types meet. Both P- and N- types are conductive to electricity. However, when they are combined or meet in their junction, they are nonconductive. This is called the Depletion Zone.
In October of 2000 the Research and Development team at Bell Labs in Murray Hill, New Jersey experienced a breakthrough in laser development. Their research team developed a semiconductor laser that emits light in the far sides of the infrared spectrum. This region is both invisible to the naked eye and is difficult area to get lasers to work. The "world's longest wavelength semiconductor laser" is useful in detecting chemicals and pollutants in the smallest amounts. Pollutants in both the stratosphere and on Earth can be analysed by spectroscopes. Because gasses pass through laser light selectively, the analysis by chemists is similar to fingerprints collected by detectives.
Besides the highly scientific applications involving chemical analysis, semiconductor lasers have more practical applications, such as in laser printers for computers as well as in compact disc players.
Answers.com. "Semiconductor Laser," "Laser Diode." Copyright 2006. Answers Corporation. September 25, 2006. http://www.answers.com/topic/laser-diode
Riordan, Michael and Lillian Hoddeson; Feynman. "Semiconductors." Copyright 1999. ScienCentral, Inc., American Institute of Physics. PBS.org. September 25, 2006. http://www.pbs.org/transistor/science/events/semic s.html
Wikipedia. "P-N Junction." Wikimedia Foundation, Inc. September 9, 2006. September 25, 2006. http://en.wikipedia.org/wiki/P-n_junction
Bellis, Mary. "History of Lasers." About, Inc. Copyright 2006. New York Times Company. September 25, 2006. http://inventors.about.com/od/lstartinventions/a/l aser.htm
Press release. "Bell Labs researchers build world's longest wavelength semiconductor laser." Lucent Technologies. October 18, 2000. Copyright 2006. Lucent Technologies. September 25, 2006. http://www.lucent.com/press/1000/001018.bla.html
Weschler, Matthew. "How Lasers Work." How Stuff Works. Copyright 2006. HowStuffWorks, Inc. HSW Media Network. September 25, 2006. http://science.howstuffworks.com/laser7.htm
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