This Nobel Laureate Paved the Approach for Excessive-Depth Lasers

Rising up, Donna Strickland had one objective in thoughts: Earn a Ph.D. However she didn’t know what topic she needed to pursue till she started her undergraduate research in physics at McMaster College, in Hamilton, Ont., Canada. It was there that she bought concerned about learning lasers after taking a course on the topic.

The subject appeared “actually cool—like one thing from a science-fiction novel,” Strickland says. Little did she know that her newfound ardour would at some point earn her a Nobel Prize in physics.

Whereas conducting analysis in optics for her doctorate on the College of Rochester, in New York, Strickland labored with French physicist Gérard Mourou, a laser pioneer and Nobel laureate. Mourou led the event of the Excessive Mild Infrastructure community of physics laboratories constructed to generate and research intense laser gentle. Collectively, whereas experimenting with how one can enhance a laser’s peak energy with out damaging it, they invented the chirped-pulse amplification method. CPA, which produces brief laser pulses that attain excessive depth, now’s utilized in corrective eye surgical procedure, medical imaging, smartphone manufacturing, and plenty of extra functions.

Strickland and Mourou shared the 2018 Nobel Prize in physics with IEEE Life Fellow Arthur Ashkin, who invented a separate know-how: “optical tweezers,” which use low-power laser beams to govern residing cells and different tiny objects.

Receiving the Nobel was “life-changing,” Strickland says, including, “Your life can change in a single day with out you being prepared for it.”

Her invention additionally earned her this yr’s IEEE Honorary Membership, which is sponsored by IEEE. She says the popularity is particular as a result of her colleagues nominated her for it.

“Donna’s work has been transformative. Her seminal analysis on chirped-pulse amplification is the gold commonplace of analysis,” one in all her award endorsers stated. “Moreover, she is a real position mannequin to legions of engineers all over the world. She is a particularly giving particular person and a shining instance of what an IEEE honorary member must be.”

Strickland is a physics professor on the College of Waterloo, in Ontario, the place she leads a gaggle of researchers that’s growing high-intensity laser programs for nonlinear optics investigations resembling producing midinfrared pulses by distinction frequency mixing and learning the multifrequency Raman era method.

Donna Strickland receives the 2018 Nobel Prize in physics from King Carl Gustaf of Sweden, on the Stockholm Live performance Corridor.Henrik Montgomery/TT Information Company/Getty Photos

Paving the best way for high-intensity lasers

After graduating in 1981 with a bachelor’s engineering diploma in physics from McMaster, Strickland moved to New York to pursue a doctorate in optics on the College of Rochester, which on the time was thought-about one of many high colleges for learning laser optics. She joined Mourou on the college’s Laboratory for Laser Energetics, the place he was searching for methods to extend lasers’ depth (its optical energy) with out damaging the gadget.

Pulsed lasers can focus gentle onto a small space for a short while to supply energy. Peak intensities elevated quickly for a number of years after physicist Theodore Maiman demonstrated the first laser in 1960. However the intensities plateaued for greater than a decade after 1970 as a result of amplifying the sunshine previous a sure level broken the laser.

In his analysis on how gentle interacts with matter, Mourou hypothesized in 1983 that spacing out and augmenting pulses earlier than bringing them again collectively may lead to higher-intensity laser pulses with out harm. However he didn’t know how one can accomplish it, Strickland says. So for her doctoral analysis, she examined his speculation with totally different laser programs. None of her experiments labored, nonetheless.

“Donna is a real position mannequin to legions of engineers all over the world. She is a particularly giving particular person and a shining instance of what an IEEE honorary member must be.”

It wasn’t till Strickland and Mourou attended the 1984 Worldwide Convention on Ultrafast Phenomena that they discovered the answer. The biannual occasion brings collectively scientists who’re growing instruments, methodologies, and methods used to check processes in atoms, molecules, or supplies that happen in millionths of a billionth of a second or quicker.

Strickland and Mourou attended a presentation on the convention concerning the newly developed optical fiber pulse compression of neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers. With the method, 100-picosecond pulses may very well be compressed to 1 ps utilizing nonlinear optics in an optical fiber to extend a laser’s spectral bandwidth. It was discovered that compression was most profitable when the pulses have been allowed to stretch by way of dispersion within the fiber.

“I used to be utilizing those self same lasers for my experiments,” Strickland recalled.

She and Mourou discovered how she may safely create the high-intensity pulse: The heart beat wanted to be stretched earlier than it was amplified relatively than afterward, as what had been completed. Stretching the heartbeat meant it may very well be recompressed to supply the specified depth.

To check her idea, Stickland and Mourou constructed a system on the Laboratory for Laser Energetics that was composed of a 2-watt Nd:YAG laser, 1.4 kilometers of optical fiber, an amplifier, and a pair of parallel gratings.

The Nd:YAG laser pumped a brief pulse at 100 ps into the optical fiber. As the rate of sunshine depends on wavelength, the crimson element of the sunshine propagates quicker than the blue throughout the fiber.

That’s known as a “chirped pulse,” Strickland says, as a result of a chicken’s chirp has the same frequency construction.

The chirped pulse makes the period of the heartbeat longer and spreads out the depth in order that it doesn’t harm the laser. The stretched, lower-energy density pulse was then amplified and handed by way of a pair of parallel diffraction gratings—which allowed the trailing blue element to catch as much as the crimson. Each have been reassembled by reflecting off the gratings. The reassembled pulse was thrice extra highly effective than the unique one, Stickland says.

The method, which was named after the chirped pulse, has since paved the best way for the shortest and most intense laser pulses ever created, making it potential to construct extra compact and exact laser programs.

Strickland and Mourou’s 1985 paper “Compression of Amplified Chirped Optical Pulses,” was revealed in Optics Communications. It was Strickland’s first revealed analysis paper.

From Princeton to Waterloo

After serving to develop CPA, Strickland nonetheless wasn’t certain what profession path to pursue. She sought recommendation from her colleagues, and one instructed her that Paul Corkum, a physicist who labored within the Canadian Nationwide Analysis Council’s ultrafast-phenomena division, was getting his first postdoctoral analysis fellow that yr. Corkum, who specialised in laser science, pioneered the event of attosecond physics. Strickland appreciated the sound of that.

“I bear in mind telling the opposite doctoral candidates in my analysis lab that Corkum could not know my title but, however I used to be going to be his second postdoc,” she says. She bought her dream job in 1988 and labored for him for 3 years.

In 1991 she grew to become a physicist on the Lawrence Livermore Nationwide Laboratory, a U.S. Division of Vitality facility in California.

Whereas she lived on the West Coast, her husband, a physicist, lived on the East Coast, working at Bell Labs in Murray Hill, N.J.

After spending a yr aside, Strickland moved to New Jersey to hitch the technical workers at Princeton’s Superior Expertise Heart for Photonics and Opto-electronic Supplies. She labored with electrical engineers, mechanical engineers, and chemists there, she says, and “if they’d a laser, I helped them out.” She helped a professor construct a CPA laser and assisted a analysis group that was conducting nonlinear optical characterization of a brand new pulse amplifying materials.

Strickland says she thought she’d be working at Princeton till she retired, however after her husband left Bell Labs in 1996, they returned to Canada. Strickland joined the College of Waterloo’s physics division as an assistant professor. She was promoted to affiliate professor in 2002. From 2007 to 2013, she served as affiliate chair of the division.

“After I was younger, I simply needed to get a Ph.D. and keep in class,” Strickland says. “Being a professor is the subsequent smartest thing to being a scholar.”

She obtained the IEEE Honorary Membership on 5 Might on the IEEE Imaginative and prescient, Innovation, and Challenges Summit and Honors Ceremony, held on the Hilton Atlanta.