- Half of the 2018 Nobel Prize for Physics has been awarded to Gérard Mourou and Donna Strickland for their method of generating high-intensity, ultra-short optical pulses
- Ultra-fast laser physics key to development of future electronics
The technique developed by Mourou and Strickland has had enormous impact across the fields of chemistry, physics and biology, and provides the basis for important scientific approaches used in FLEET’s research.
Ultra-fast laser physics at Swinburne
FLEET CI Jeff Davis at Swinburne uses laser pulses just a few quadrillionths of a second in duration to investigate novel, complex materials that could be used in a future generation of low-energy electronics.
The field of study is referred to ultrafast ‘femtosecond’ spectroscopy (a femtosecond is a millionth of a billionth of a second in duration).
“These extremely short-duration pulses are necessary to measure the evolution of sub-atomic particles such as electrons,” explains Professor Davis.
“When you want to measure how fast something is moving, you need a starter’s gun to set things going and something to stop the clock.
“In a 100m race, this is straightforward because the time taken to run 100m is slow compared with how fast you can push the buttons on a stopwatch.
“But when you want to measure the precise evolution of electrons, which can change their properties or their state in femtoseconds, you need to be able to start and stop the clock much, much faster. We use femtosecond laser pulses to achieve this.”
Swinburne University of Technology has the highest concentration of ultrafast laser systems in the southern hemisphere, many relying on the technique developed by Strickland and Mourou. In fact, Swinburne was the first lab in Australia to install one of these amplified laser systems, in 1998.
Within FLEET, ultrafast spectroscopy delivers fundamental understanding of novel materials. But the technique is flexible enough to have added similar value in a wide range of fields, from chemistry and biology through to physics and materials science.
Chirped-pulse amplification
The development of chirped-pulse amplification (CPA) by Mourou and Strickland is key to that flexibility, and has thus enabled scientific discoveries in a number of fields.
CPA allows high-energy pulses to be produced every microsecond, ie, a million pulses per second, which means that spectroscopy measurements can be performed in a reasonable time, allowing sufficient data to be acquired to minimise noise levels on weak signals.
This also makes it possible to vary different control parameters to build up a comprehensive picture of the important factors affecting the dynamics and mechanisms of the specific process of interest.
The extremely high energy of the laser pulse ensures that nonlinear processes are efficient, and this allows researchers to ‘tune’ the wavelength: producing laser light right across the electromagnetic spectrum, from far infrared, through visible light, ultraviolet and even X-rays.
Probing properties and forcing temporary states at FLEET
As well as probing novel and complex materials, these high-energy ultrashort laser pulses can be used to control the properties of these materials, and even drive them to change state, becoming novel quantum states of matter.
“In FLEET, we are developing ways to change two-dimensional materials from being trivial insulators into what are known as topological insulators, and back again,” explains Professor Davis.
Topological insulators are a relatively new state of matter, recognised by the 2016 Nobel Prize in Physics, which have the fascinating property that they don’t conduct electricity through their interior, but around the edges the electrical current can flow without resistance, and hence without energy loss.
FLEET will take advantage of this unique property to develop a new generation of topological electronic devices that do not waste energy as they switch.
The proposed technology could also potentially switch much faster than current, silicon-based electronics.
“Ultrafast laser pulses allows exquisite control over the properties of the material, giving us the potential for ultrafast switching,” says Davis.
“This exquisite control and our ultrafast measurement of dynamics will allow us to fully understand these phase transitions, allowing us to optimise their control in future devices.
“So, it’s fundamental science, but with an immediate application,” explains Davis.
“These experiments enhance our fundamental understanding of topological phase transitions, and we use this knowledge in our investigations of future ultra-low energy, topologically-based electronics.”
FLEET is an Australian Research Council-funded research centre bringing together over a hundred Australian and international experts to develop a new generation of ultra-low energy electronics.
The impetus behind such work is the increasing challenge of energy used in computation, which uses 5–8% of global electricity and is doubling every decade.
More information
- Contact Prof Jeffrey Davis jdavis@swin.edu.au
- Visit Swinburne’s Ultrafast Spectroscopy group
- Visit FLEET.org.au
- Connect at @FLEETCentre
- Watch future solutions to computation energy use
- Subscribe to to FLEET news