The 2018 Nobel Prize in Physics — which was divided by two — was an ode to lasers. One half of the honor was awarded to Gérard Mourou, emeritus faculty of the University of Michigan, and Donna Strickland, a professor at the University of Waterloo in Ontario, Canada, for their successful creation of chirped pulse amplification or CPA; a method for generating high intensity, ultra-short optical pulses. The other half of the prize went to Arthur Ashkin, an American physicist associated with Bell Laboratories, for his invention of “tweezers” which utilize beams of laser light to grab living cells, molecules, and even atoms.
Strickland is the first woman in 55 years to be awarded the Nobel Prize in physics and the third woman to be recognized in the award’s history. She is also one of the few people to be honored for research that she undertook as a graduate student at the University of Rochester in the 1980s. U-M’s Mourou was her adviser.
Power has consistently been at the core of technological advancement. And what initially began as experiments under conditions that Mourou has described as rather “dated” ended up leading to the most intense laser pulses ever created. CPA has the ability to amplify the peak power of an ultrashort laser pulse to a level that exceeds several petawatts (a petawatt is approximately 1/200th of the total power of sunlight striking the earth’s atmosphere). It’s a level of amplification that has opened the door to a wide range of applications, in both medicine and industry, never before possible through lasers. Some notable ones include cutting a patient’s cornea in a bladeless form of Lasik eye surgery and machining glass parts that are used in cell phones.
Chirped Pulse Amplification has led to the most intense laser pulses ever created.
These amplified lasers also have the capacity to generate elementary particles like protons. Mourou predicts proton therapy, in which beams of protons rather than X-rays are used to treat cancer, is going to be extremely important in the future. In standard X-ray therapy, lasers are usually not targeted enough to only burn tumors, and often end up burning healthy tissue as well. With proton therapy, though, laser beams are so precise that they can be focused directly on the tumor while preserving the healthy tissue surrounding it.
With regard to future work, Mourou says, “I absolutely plan to take this research forward. We want to modify the laser architecture to go even higher so that we might be able to materialize light and vacuums.” Like CPA, these are processes that seem fundamental, but will have practical applications that are monumental.