[ad_1]
Over the last fifty years, laser technology has become a multibillion dollar global industry and has been used in many areas, from optical disc drives to barcode readers, to surgical and surgical equipment. welding.
Not to mention those laser pointers that entertain and confuse your cat.
The lasers are about to take another step forward: Case Western Reserve University researchers, in collaboration with partners around the world, have been able to control the direction of the beamwind. a laser by applying an external voltage.
This is an historic first among scientists who have experimented with what they call "random lasers" over the past 15 years.
"There is still a lot of work to be done, but it is a first clear proof of a random transistor laser, in which the emission of the laser can be routed and directed in applying external voltage, "said Giuseppe Strangi, a professor and researcher specializing in surfaces in Ohio in Ohio. advanced materials at Case Western Reserve University.
Strangi, who led the research, and his collaborators recently presented their findings in an article published in the journal Nature Communications. The project, funded by the National Academy of Sciences of Finland, aimed to overcome some of the physical limitations inherent in the second generation of lasers.
Laser success, laser limitations
The history of laser technology has been very fast because the unique light source has revolutionized virtually every area of modern life, including telecommunications, biomedicine and measurement technology.
But laser technology has also been hampered by significant flaws: not only do users have to physically manipulate the light-projecting device to move a laser, but to function, they require precise alignment of the components, making them expensive to produce. .
These limitations may soon be eliminated: Strangi and its research partners in Italy, Finland and the United Kingdom have recently shown a new way to generate and manipulate random laser light, including at the nanoscale.
This could eventually lead to a more precise and less invasive medical procedure or to a rerouting of an optical fiber communication line with a simple dial, Strangi said.
"Random" lasers have been improved
So, how do lasers work?
Conventional lasers consist of an optical cavity or an opening in a given device. Inside this cavity is a photoluminescent material that emits and amplifies light and a pair of mirrors. Mirrors force photons, or light particles, to bounce at a specific frequency to produce the red laser beam emitted by the laser.
"But if we wanted to miniaturize it, get rid of the mirrors, create a laser without cavity and go down to the nanoscale? He asked. "It was a problem in the real world and why we could not go further until the turn of this century with random lasers."
Random lasers, which have been the subject of serious research for about 15 years, differ from the original technology unveiled for the first time in 1960, mainly by the fact that they do not rely on this mirror cavity.
In random lasers, photons emitted in many directions are rather scattered by projecting light into a liquid crystal medium, guiding the resulting particles with this beam of light. Therefore, the large mirror structure required in traditional applications is not necessary.
The resulting wave – called "soliton" by Strangi and the researchers – serves as a channel for scattered photons to follow them, maintaining an orderly and focused path.
One way to understand how this works is to consider a clear-particle version of the "solitary waves" that surfers (and freshwater fish) can ride when rivers and streams collide in some estuaries, Strangi said. .
Finally, the research hit the liquid crystal with an electrical signal, which allows the user to "direct" the laser with a dial, instead of moving the entire structure.
That's the great development of this team, said Strangi.
"That's why we call it" transistor "because a weak signal (the soliton) controls a powerful signal: the laser output." Said Strangi. "Lasers and transistors have been the two breakthrough technologies that revolutionized the last century and we discovered that they are both nested in the same physical system."
The researchers believe that their results will bring random lasers closer to practical applications in spectroscopy (used in physical and analytical chemistry, as well as in astronomy and remote sensing), as well as in various forms of scanning and biomedical procedures.
Other researchers involved in the project include Sreekanth Perumbilavil, Raouf Barboza and Martti Kauranen from the Tampere University of Technology in Tampere, Finland; Armando Piccardi, of the nonlinear optics and optoelectronics laboratory of Roma Tre University in Rome; Gaetano Assanto, who coordinated the research in Finnish and Italian universities; and Oleksandr Buchnev, optoelectronics research center at the University of Southhampton, UK.
Source link
