The Ultrafast Optical Processing Group at INRS (Institut national de la recherche scientifique) has redefined the limitations and constraints for ultra-fast pulsed lasers. As reported in Nature Photonics, researchers from the team of Prof. Roberto Morandotti have produced the first pulsed passively mode-locked nanosecond laser, with a record-low and transform-limited spectral width of 105 MHz--more than one hundred times lower than any mode-locked laser to date. With a compact architecture, modest power requirements, and the unique ability to resolve the full laser spectrum in the radio frequency (RF) domain, the laser paves the way towards full on-chip integration for novel sensing and spectroscopy implementations.
Lasers emitting intense light-pulse trains have enabled the observation of numerous phenomena in many different research disciplines, and are the basis of state-of-the-art experiments in modern physics, chemistry, biology, and astronomy. However, high pulse intensities with low repetition rates come at the expense of mediocre noise properties.
This is where passively mode-locked laser systems come in: They are the optimal choice for generating low-noise optical pulse trains. Such systems have, for example, made it possible to create stable optical frequency references for metrology (Nobel Prize, 2005) as well as intense ultra-short pulses (i.e., single-cycle pulses in the attosecond regime) for the study of high-intensity light-matter interactions.
While many mode-locking techniques have been demonstrated, mainly aimed at creating increasingly shorter pulses with broader spectra, little progress has been achieved so far in tackling the opposite problem: the generation of stable nanosecond narrow-bandwidth pulsed sources.
In their latest publication, the INRS research team presents a novel laser architecture that capitalizes on recent advances in nonlinear micro-cavity optics, pushing the boundaries further. Specifically, they exploit the narrowband filter characteristic of integrated microring resonators which, in addition to enabling high nonlinear phase shifts, make it possible to generate nanosecond pulses though mode-locking.
"The pulsed laser output generated has a spectral bandwidth so narrow it is inaccessible with state-of-the-art optical spectrum analyzers," says Michael Kues, postdoctoral fellow and principal author of the study. To characterize the laser's bandwidth, the researchers instead used a coherent optical beating technique. The record-low laser bandwidth made it possible, for the first time, to measure the full spectral characteristics of a mode-locked laser in the RF domain using widely available RF electronics only and confirming, in turn, the laser's strong temporal coherence.
Such stable narrow-bandwidth nanosecond pulsed sources are desirable for many sensing and microscopy applications, as well as for the efficient excitation of atoms and molecules (typically featuring narrow excitation bandwidths). From a fundamental perspective, the low and tractable number of optical laser modes, combined with the RF-accessibility of the associated spectrum, make the team's newly developed laser highly conducive to further study of both nonlinear mode coupling and complex mode-locking regimes.
ABOUT THE PUBLICATION
Published in Nature Photonics, the article "Passively mode-locked laser with an ultra-narrow spectral width" (DOI: 10.1038/nphoton.2016.271) is the result of an international research partnership involving researchers from Quebec, the United Kingdom, China, Russia, and Australia. The principal author is Michael Kues of the INRS Centre Énergie Matériaux Télécommunications. The study was produced by the Ultra-Fast Optical Processing Group led by Professor Roberto Morandotti and was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) through the Steacie, Canada Chair, and Discovery Grants programs, by the MESI PSR-SIIRI Initiative in Quebec, and by the Australian Research Council Discovery Projects scheme.
Institut national de la recherche scientifique (INRS) is a graduate-level research and training university and ranks first in Canada for research intensity (average funding per professor). INRS brings together some 150 professors and close to 700 students and postdoctoral fellows at its four centres in Montreal, Quebec City, Laval, and Varennes. Its basic research is essential to the advancement of science in Quebec and internationally, and its research teams play a key role in the development of concrete solutions to the problems faced by our society.
Stephanie Thibault, Communications Advisor, INRS, email@example.com, +1 514-499-6612
Roberto Morandotti | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine