Laser has been found since the 1960s and until now has been used in manyfields. There is one characteristic of a laser to date has yet to be solved, resultingin a white laser. White laser is a laser that emits white light beam. Everywhere, all over the world, as long as this laser beam only consists of one file color: red or green. But it used to be!
A group of researchers at Arizona State University has paved the way to the invention of the laser. The Group of researchers has successfully showed thatsemiconductor lasers can emit x-ray spectrum containing all the spectrum ofvisible light rays. If all the spectrum of visible light can be emitted, thentheoretically, white light could be generated because white light is a combination of the entire spectrum of those colors.
Researchers who are members of the group have made a sheet of very thinmaterial on the size of the nano, so called nano-sheet. Nano-sheet this is thesemiconductor layers that are roughly equal to approximately 1/50 times the thickness of a human hair. Thick slabs of the nano itself is approximately equal to 1/1000 thick human hair. The nano-sheets made up of three parallelsegments, each segment supports laser surgery on one base color. Nano-sheetis capable of emitting a beam of any color, which can range from disetel-setelcolors red, green, and blue, including the combination of colors between. If the overall wave field of color can be merged, then it can be laser color white.
Researchers within the group, engineers at Arizona State University engineering school, has published the results of their findings in the online journal NatureNanotechnology Edition July 27, 2015. Cun-Zheng Ning, a professor at theSchool of Electrical, Computer and Energy Engineering, is the author of the paper "A monolithic white laser", along with students doktoralnya SunayTurkdogan Fan, Fan, Zhincheng Liu and David Shelhammer. Turkdogan and Liucompleted their doctoral program after completing the research.
Potential Applications
The high level of technology has been directing the laser becomes one step closer to be utilized as the primary light source and potentially replace oralternatively of light diode (LED). Laser light far brighter, more efficient, andpotentially could produce accurate colors and clear especially for the purposes of the display monitor as a computer monitor or television. Ning team have shown that laser structures they create have the color coverage of about 70% more compared to the scope of colours on the screen monitor industrystandards today.
Another important application of the results of their findings are on the potential of its use in the development of a visible light communication have in common with the lighting system. This means that the structure they found, can be used both for lighting purposes or for communication. The technology, which is currently being developed by experts, is attempting is called Li-Fi forlight-based wireless communications, a rival to Wi-Fi. Wi-Fi has we know iswireless communication systems based on radio wave. Li-Fi can be 10 timesfaster than Wi-Fi now, Li-Fi white with a laser can be 10 to 100 times faster than with a Li-Fi based LEDS that are currently in development.
Initial efforts the laser making white and the challenge for lighting applications
If you have been reading how the workings of the laser, then you certainlyrealize that the concept of this seemingly abstruse white laser because the lightcomes from a laser so far contains only one color only, i.e. only one narrowparticular wavelengths of the spectrum of electromagnetic waves. While we know that the white light is seen as a composite of all wavelengths of the visiblespectrum. LED-based lights on a regular, a blue LED with phosphor materialcoated to change most of these into light blue light green, yellow, and red. Mixthese colors will be perceived by humans as white light so it can be used as a tool of information in General.
Sandia National laboratories in 2011 has been producing high quality white lightlamps using four separate large laser. Researchers at the Sandia National Laboratory and then demonstrate that it turns out the human eye has the samelevel of comfort on the white light generated by a laser diode with this white light produced by LED lights. These results became an inspiration for other researchers to be able to further improve the technology of laser-based light.
"Even though a demonstration of proof of concept of the las
"Although the demonstration of proof of concept of this impressive white laser, laser in themselves cannot be used for the purpose for display space or shinesmonitors," said Ning. "It takes a very small semiconductor material to be able toemit laser beams in all spectral colors or white in colour."
Semiconductors, which are usually solid chemical element or a mixture that isarrayed in Crystal form, is currently widely been used as a major component of the brain in the computer and telecommunications systems. Semiconductoroptical characteristics that are interesting and are used in making lasers andLEDS as they may emit rays of light with a certain color or when a potential difference is imposed on the semiconductor. Material emitting the most widely used as semiconductors gallium indium nitride is, although other materials such as cadmium sulfide and cadmium selenide is also often used to emit the color ofvisible light.
The main challenge at this semiconductor utilization is, as noted by scientists,lies in how to grow semiconductor emitting materials and semiconductormaterials how to make this work or emitting varied colours. Usually, a specificsemiconductor it only emits a single color--blue, green, or red — defined by the distinctive atomic structure and energy ribbons gap.
"The lattice Constants" in Crystal stated the distance between atoms in a crystal.To generate all possible wavelengths in the visible spectrum, you need somesemiconductor lattice constants have the high value varieties including energygap variation value.
"Our goal is to obtain a single semiconductor which can perform the function ofa laser for three colors laser base. The semiconductor should be quite small, so people can mengindera overall color mixture, not three different colors, "saidFan. "But it is not easy".
"The main Challenge is the lattice mismatch, or crystal lattice constants, which are different for each material that is required," said Liu. "We haven't been able to cultivate a different semiconductor crystals simultaneously with a high enough quality, using traditional techniques, if the lattice constant of crystalsthat have values that are very different from each other."
Solutions are highly expected, according to Ning, is a single semiconductorstructure that exudes all the colors needed. Ning, together with studentdoktoralnya finally switch on nanotechnology for historic momentum to achievethem. The idea is that at the level of the nanometre, a large lattice mismatchmay be tolerated better than using traditional growing techniques in solidmaterials. At the level of the nanometre, high quality crystals can be grown even with lattice constant mismatch.
Aware of this unique Group, Ning began to search for a number of special characteristics, such as nanomaterial wire nano, nano or sheet, since ten years ago. Together with his student, Ning has been researching various types ofnanomaterial nanomaterial to be able to find the most profitable to examine thegrowth of high-quality crystals of different materials.
Six years ago, with the help of funding from the Army Research Office, they eventually may show that the material the nano wire with Ribbon of energy gaprange is wide indeed can be grown on a single substrate with a length ofapproximately 1 cm. Some time later, they managed to make the Green and Redlasers that work simultaneously with the use of nano-sheet and wire nanosemiconductors. This achievement triggers Ning to learn whether a single whitelasers really can be generated.
Rays of blue color, the color of which is needed to produce white, proved to bea challenge with the greatest energy Ribbon the large gap and have the properties of different materials. (Read also: Nobel Prize in physics 2001: the invention of the blue LED and Let There Be A High Efficiency Light)
"We have been fighting almost two years to develop a material that can emit ablue color in the form of nano-sheet, which is necessary to demonstrate laserwhite," Turkdogan said, who is currently an Assistant Professor at the University of Yalova in Turkey.
After going through a thorough research, group researcher Ning until finally ona strategy that is making the first form is desired, then the mengonversinya becontains mixed (alloy) that can fit to emit blue light. Turkdogan said, "based onour knowledge, our growth strategy it is a unique demonstration of the growingprocess of first appealing called dual ion exchange process which permits the formation of structure desired."
The strategy of structural form of separation and composition like this, representing the occurrence of a fundamental change in terms of growthstrategy and is a significant breakthrough ultimately allowed the growth of asingle structure that contains three different types of semiconductors that canemit all the colors needed so that white becomes color laser is possible.
Although evidence of the beginning is very important, the most significantchallenges that will be faced is producing laser white as above to be utilized as a source of lighting in the real life or on the application for the purposes of the display monitor. One of the next important steps that need to be accomplished to this goal is to produce a white laser with battery power source. For the purposes of demonstration, the researchers had to use a laser light for pumpingelectrons in order to generate the propagation of light. Experimental effortsabove has shown that the key to the achievement of white laser materialrequirements are needed and this will be a cornerstone for laser beam can produce white work using household electricity consumption.
Well, do you, the reader of this blog, have ideas to develop and give a touchmore distant that we are closer to realizing the dream?
Source:
Arizona State University. "The world's first white lasers demonstrated: Moreluminous, energy efficient than LEDs, white lasers look to be the future inlighting and Li-Fi, or light-based wireless communication." ScienceDaily.ScienceDaily, 29 July 2015. .
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