NOnly a few inventions have inspired science and technology as much as those of the laser almost sixty years ago. At first ridiculed as a solution to a problem that still has to be sought, the special light source has now conquered almost all areas. In medicine, telecommunications and consumer electronics, high-energy, highly concentrated laser beams are just as indispensable as in modern measuring technology and industrial manufacturing and material processing. The applications of the laser are as diverse as the various existing types of lasers. While the smallest laser is barely larger than a grain of sand, the most powerful laser devices now fill entire halls. The latter generate extremely high light intensities and short light pulses. But most developments would be without the invention of two laser pioneers – Donna Strickland and Gérard Mourou – unthinkable.
Honored with the Nobel Prize for Physics only last year, the two researchers visited Lindau for the first time this year. Especially on the lecture by Donna Strickland (see video) the young scientists were curious. Because the native Canadian is only the third woman after Marie Curie and Maria Goeppert-Meyer, who has received the most important prize in physics. “It does not matter if a woman or a man is awarded the Nobel Prize,” said Donna Strickland in the Lindau Island Hall.
It would be especially important for the scientific achievements. She had always had to do with male teachers and colleagues. One of her main sponsors was Gérard Mourou. The Frenchman was researching at the University of Rochester in New York, when the native Canadian joined him after completing her master's degree in 1981 to start a doctoral thesis.
A barrier falls
Mourou has been working in Rochester since 1979 with solid state lasers that emit short bursts of radiation. At that time the physicists did not progress any further in this field. The laser pulses, which lasted only a fraction of a second, could not be further amplified than continuous laser beams without damaging the medium needed to produce them. Strickland and Mourou were looking for a way to increase the number of light particles in a laser pulse and increase their intensity. They found him reading an article on radar technology: Take a laser pulse, stretch it in time and amplify it to then re-compress the pulse and reduce its duration. By upsetting more photons are pressed into a smaller volume. The original laser pulse is thereby shorter and considerably more intense. The amplifier medium is spared because the peak power of the time-expanded pulse is lowered below the destructive threshold.
In fact, the process was difficult to achieve. All the components that passed through the pulses needed to be matched. The glass fiber that was necessary to spread the incident laser pulses prepared the headache. It was not allowed to lose any light on the way. It was one of Strickland's tasks to find a solution. First attempts with a 2.5 kilometer long fiber failed because no laser pulses appeared at the end. Somewhere the optical fiber was broken. Strickland broke the fiber in half. And it worked: Also a length of 1.4 kilometers was enough for the desired stretching effect completely.
. (tagsToTranslate) Donna Strickland (t) Marie Curie (t) Maria Goeppert-Meyer (t) University of Rochester (t) Laser Pulse (t) Laser (t) Future Laboratory