Rediscovering the physicist born a century ago in Far North Queensland who went on to win a Nobel Prize for his role in the invention of the laser.
When he died in 2002, Prokhorov was a nation
Australian physicists are now working to change that.
The Australian Optical Society (AOS) sessions at the Congress on Monday morning will be held in honour of Prokhorov— AOS President, Professor Stephen Collins can speak to the topic.
The centenary of Prokhorov’s birth was also celebrated in a series of spectacular laser-shows in Far North Queensland as part of National Science Week.
Prokhorov’s contributions to physics have changed our lives. With fellow Nobel Laureates Nicolay Basov (USSR) and Charles Townes (USA), Aleksandr Prokhorov developed the technologies that made the laser possible.
Today, lasers are ubiquitous—from barcode scanners to 3D printers, manufacturing, surgery, telecommunications and even measuring gravitational waves.
It’s hard to believe that when lasers were first discovered no-one could think of any use for them. In fact they were famously described as a “solution looking for a problem.” And for many decades before that, scientists doubted they could ever be built.
Read on for more about the science, the impacts of the laser today, Prokhorov’s life, contacts and available images.
The science
A laser emits intense light of a particular wavelength in a very narrow band.
Einstein established the quantum theory behind the laser in 1917, showing that a photon of a particular energy could knock an electron to a lower energy level, releasing its energy as another photon. In theory, the result—within a substance held in a particular excited state—would be a constant flow of photons of the same energy.
Named ‘stimulated emission’, the theoretical process was one of many revolutionary predictions of the new field of quantum mechanics. However, at that point most scientists said such a device could never be built.
At the Soviet Institute of Atomic Energy, Prokhorov and Basov developed methods to produce and maintain that necessary constant, excited state.
Then, by introducing mirrors at either end of a cylinder of excited material, they bounced the emitted photons back and forth to stimulate emission of even more photons. By precisely controlling the distance between the two mirrors, the scientists could establish a standing wave, so that only radiation of a particular wavelength was amplified.
From one end of the device a partially-silvered mirror allowed some photons to escape, creating a beam of intense light at a single wavelength. The laser was born.
Prokhorov and Basov worked with longer-wavelength ‘microwave’ radiation, so the first device built was a maser (microwave amplification by stimulated emission of radiation). Subsequent research extended the technology to visible wavelengths—the ‘laser’ (light amplification by stimulated emission of radiation). Masers are still used today in atomic clocks such as those at the heart of GPS.
Lasers now
Despite Prokhorov, Basov and Townes receiving the Nobel Prize in 1964 for their work, lasers were for years seen as a clever invention with no practical use—famously described as a “solution looking for a problem.”
How wrong they were. Today, the impacts of laser technology include:
- Manufacturing, where laser cutting has enormously reduced both the time and cost of line production parts, allowing technology to become affordable
- Medicine, where tightly controlled lasers allow for precise surgery—even within a patient’s organs or on the retina at the back of the eye.
- Measurement, including at the most-basic level levelling land for construction, but most recently the incredibly precise measurements at LIGO that allowed gravitational waves to be measured. Australian physicists helped develop the laser system at LIGO that can measure distortion of only one thousandth of the width of a proton over a 4km length.
Plus, applications including well-known, laser-based cosmetics, 3D printing, DVDs (and CD players for those who remember them), military devices, visual displays, barcode scanners and research applications.
Biography
Alexander Prokhorov’s family fled to Australia as refugees from Tsarist Russia, settling in the Atherton Tablelands in Queensland, where young Aleksandr was born in 1916. The family returned home in 1923 following the Russian Revolution, where after finishing school Alexander studied radio wave propagation before serving in the infantry during WW2. He was twice wounded during that war.
Returning to physics afterwards, he eventually turned to the problem of quantum oscillation, and with colleague Nikolay Basov developed the optical pumping technique that made masers (the microwave predecessor of the laser) feasible.
The work was also significant as the first practical demonstration of quantum physics.
Alexander Prokhorov, with his collaborator Basov and US researcher Charles Townes, received the 1964 Nobel Prize for Physics “for fundamental work in the field of quantum electronics, which has led to the construction of oscillators and amplifiers based on the maser-laser principle.”
In addition to the Nobel Prize, Prokhorov was awarded the USSR’s highest civilian award (Gold Star Hero of Socialist Labour), twice, the Lomosonov gold medal for outstanding achievements in physics, highest distinction by the Optical Society of America, and was chief editor of the Great Soviet Encyclopedia. He was decorated three times for his service during WW2, including receiving the Medal of Valour for bravery.
Prokhorov is part of an intriguing group that excelled in science after coming to Australia seeking refuge from danger. The list includes fellow Nobel Laureate Bernard Katz (Medicine), who fled Nazi Germany before WW2, immunologist Gustav Nossal whose family fled Nazi Austria in 1939, ex-CSIRO scientist San Thang who survived a dangerous boat trip from Vietnam in 1979 and is now frequently shortlisted for a future Physics Nobel, and Karl Kruszelnicki whose parents survived German concentration camps and who was born in a refugee camp in Sweden.
Prokhorov & synchrotron science
Following the War, Prokhorov returned to physics to study synchrotron radiation. A synchrotron is a huge, circular installation in which a beam of subatomic particles is accelerated to near the speed of light, and held within the ring by powerful magnetic fields.
As the accelerated particles are forced to change direction to stay within the ring, they emit intensely-bright radiation – around a million times brighter than the Sun.
The 216m-wide Australian Synchrotron in Clayton, southeast Melbourne, uses that radiation in the form of intense, tuneable, tightly-focussed beams of light that can be directed onto samples. The intense light allows researchers to see the microscopic details of crystals and minerals, cracks and defects in engineering structures, and even the intricate shapes of proteins or viruses.
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