Lasers have been becoming one of the most important technologies facilitating a number of applications and they are poised to take another step forward as scientists have managed to control the direction of a laser’s output beam by applying external voltage.
This is a historic first achieved by researchers at Case Western Reserve University, in collaboration with partners around the world. Findings of the study are published in the journal Nature Communications. The project, funded by the National Academy of Sciences of Finland, was aimed at overcoming certain physical limitations intrinsic to that second generations of lasers.
The history of laser technology has been fast-paced as the unique source of light has revolutionized virtually all areas of modern life, including telecommunications, biomedicine and measurement technology. But laser technology has also been hampered by significant shortcomings: Not only do users have to physically manipulate the device projecting the light to move a laser, but to function, they require a precise alignment of components, making them expensive to produce.
Those limitations could soon be eliminated as scientists have now demonstrated a new way to both generate and manipulate random laser light, including at nano-scale. Eventually, this could lead to a medical procedure being conducted more accurately and less invasively or re-routing a fiber optic communication line with the flip of a dial, scientists are optimistic.
Conventional lasers consist of an optical cavity, or opening, in a given device. Inside that cavity is a photoluminescent material which emits and amplifies light and a pair of mirrors. The mirrors force the photons, or light particles, to bounce back and forth at a specific frequency to produce the red laser beam we see emitting from the laser. So random lasers, which have been researched in earnest for about the last 15 years, differ from the original technology first unveiled in 1960 mostly in that they do not rely on that mirrored cavity.
In random lasers, the photons emitted in many directions are instead wrangled by shining light into a liquid-crystal medium, guiding the resulting particles with that beam of light. Therefore, there is no need for the large, mirrored structure required in traditional applications. The resulting wave–called a “soliton” by Strangi and the researchers–functions as a channel for the scattered photons to follow out, now in an orderly, concentrated path.
One way to understand how this works is by envisioning a light-particle version of the “solitary waves” that surfers (and freshwater-bound fish) can ride when rivers and ocean tide collide in certain estuaries.
Finally, the researches hit the liquid crystal with an electrical signal, which allows the user to “steer” the laser with a dial, as opposed to moving the entire structure. 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), various forms of scanning and biomedical procedures.