Optic Fiber Applied In Next-Generation Ultra-Powerful Lasers
16 August 2013
Scientists are deploying a new concept based on optic fiber to capitalize on the growing demand for super-powerful lasers for applications including nuclear simulation, medical treatment and altering the direction of thunderstorms, the Guardian has reported.
One ultra-powerful laser now being fine-tuned and waiting to be delivered from French electronics firm Thales to Romania is Cetal, which has a peak power of one petawatt (PW), or one billion MW, equalling the capacity of a million nuclear reactors. A similar device called Bella was delivered to the University of California, Berkeley, in 2012.
These next-generation lasers are extremely useful to scientists, since they are cheaper and less bulky than other devices such as synchrotron x-ray sources or particle accelerators. But despite their huge power the lasers cannot be a substitute for power stations, since the energy they generate is released in very short bursts, or pulses, that exist only a few tens of femtoseconds. These highly concentrated pulses of energy, however, could be the key to bringing science-fiction projects into reality, facilitating the discovery of new cancer treatment methods, transmutation of radioactive elements into less hazardous substances and turning atomic fusion into a new energy stream.
But despite lasers' potential to make a real difference, there are certain flaws that must be addressed. For instance, pulses are not frequent enough and they require too much electricity. In order to address these hindrances, Gerard Mourou, head of the Izest laboratory at Ecole Polytechnique in France, has turned to optic fiber. Instead of using a single monolithic road amplifier, the researcher wants to try using an array of fiber lasers to produce more frequent pulses and to ensure less energy consumption by simply extending the size of the array.
In theory this seems easy, but it's not that simple in practice since light can only be deployed if the beams in each of the fiber lasers are coherent or in phase, meaning that the lines should be no longer than about 10 nanometers. Nevertheless, Mourou managed to demonstrate that 64 fibre lasers can be controlled to produce a coherent beam. The International Coherent Amplification Network, the group of 17 labs created by Mourou, now aims to build a PW-rated array pulsing 10,000 times a second comprising a minimum of 10,000 fiber lasers.
Mourou is also upbeat that fiber lasers have the potential to transmute elements, helping nuclear plants dispose of radioactive waste by turning them into elements with a shorter half-life.