1/2018

New ultrafast measurement technique shows how lasers start from chaos

How do laser pulses emerge? A recent research paper co-authored by photonics researchers from TUT and published in Nature Photonics demonstrates how laser pulses emerge from noise as if out of nowhere and display complex collapse and oscillation dynamics before settling down to stable operation.

Goëry Genty

 

Professor Goëry Genty works in the Laboratory of Photonics at Tampere University of Technology.

 

Lasers that emit ultrashort pulses of light are critical components of technologies, such as communications and industrial processing, and have been central to fundamental Nobel Prize-winning research in physics. Although first invented in the 1960s, the exact mechanism whereby lasers actually produce such bright flashes of light has remained elusive. It has not been previously possible to look inside a laser as it is first turned on to see how the laser pulses build up from noise. However, research recently published online in Nature Photonics has demonstrated for the first time how laser pulses emerge out of nowhere from noise and then display complex collapse and oscillation dynamics before eventually settling down to stable regular operation.

“The reason why understanding these lasers has been so difficult is because the pulses they produce are typically of picosecond duration or shorter. Following the complex build-up dynamics of such short pulses for the hundreds, sometimes thousands of bursts before the laser actually stabilizes has been beyond the capability of optical measurement techniques,” says Professor Goëry Genty, who supervised the research in the Laboratory of Photonics at Tampere University of Technology (TUT).

This research was performed in collaboration between the FEMTO-ST Institute in France (CNRS and the University of Bourgogne-Franche-Comté) and the Laboratory of Photonics at TUT. The particular scientific advance that led to the novel findings is the real-time measurement of the laser temporal intensity with sub-picosecond resolution, as well as its optical spectrum with sub-nanometer resolution. By recording both these temporal and spectral properties simultaneously, an advanced computational algorithm can retrieve the complete characteristics of the underlying electromagnetic field.

Aside from providing new insights into how pulsed lasers operate, the research results have important interdisciplinary applications.

“The results provide a very convenient laboratory example of what is known as a “dissipative soliton system” which is a central concept in nonlinear science and also relevant to studies in other fields, such as biology, medicine and possibly even social sciences,” says Professor John. M. Dudley, who led the research at the University of Bourgogne-Franche-Comté.

While reconstructing the evolution of the electromagnetic field, the team observed a wide range of interaction scenarios between dissipative soliton structures emerging from noise.

“The approach we have implemented can operate at low input power levels and high speeds. The results provide a completely new window on previously unseen interactions between emerging dissipative solitons in form of collisions, merging or collapse”, Genty says.

The researchers believe that their results will allow improved design and performance of ultrafast pulsed lasers.

“This is a truly fascinating area of research where studies motivated by questions in fundamental science have the potential to have real practical impact in future photonic technology,” concludes Dudley.

The research was supported by the Academy of Finland (Grants 267576 and 298463), the Agence Nationale de la Recherche project LABEX ACTION ANR11-LABX-0001-01, and the Region of Franche-Comté Project CORPS.

Paper published in Nature Photonics: P. Ryczkowski, M. Närhi, C. Billet, J.-M. Merolla, G. Genty & J. M. Dudley, “Real-time full-field characterization of transient dissipative soliton dynamics in a mode-locked laser,” Nature Photonics (2018), doi:10.1038/s41566-018-0106-7


Photo: Valtteri Pönkkä

 
Tell a friend
Machines outperform the human ear
Machines outperform the human ear
1/2018
Machines outperform the human ear
More devices, more data – and critical research problems
More devices, more data – and critical research problems
1/2018
More devices, more data – and critical research problems
On the cusp of everyday AI
On the cusp of everyday AI
1/2018
On the cusp of everyday AI
Pure entertainment and critical safety
Pure entertainment and critical safety
1/2018
Pure entertainment and critical safety
Open a door to assist in the development of smart homes
Open a door to assist in the development of smart homes
1/2018
Open a door to assist in the development of smart homes
What does the future hold for developers of intelligent systems and software?
What does the future hold for developers of intelligent systems and software?
1/2018
What does the future hold for developers of intelligent systems and software?
First thought in the morning: Let’s do it!
First thought in the morning: Let’s do it!
1/2018
First thought in the morning: Let’s do it!
Keep your feet on the ground when you go to the cloud
Keep your feet on the ground when you go to the cloud
1/2018
Keep your feet on the ground when you go to the cloud
Serious injuries should not be overlooked
Serious injuries should not be overlooked
1/2018
Serious injuries should not be overlooked
School groups attended the European Robotics Forum: “The best day ever!”
School groups attended the European Robotics Forum: “The best day ever!”
1/2018
School groups attended the European Robotics Forum: “The best day ever!”
Campus IoT network now available
Campus IoT network now available
1/2018
Campus IoT network now available
Immersive Media goes Disruptive!
Immersive Media goes Disruptive!
1/2018
Immersive Media goes Disruptive!

Tampere University of Technology is at the leading edge of technology development and a sought-after collaboration partner among the scientific and business communities. The University produces competent graduates who enter careers in the different sectors of society.

Visiting address
Korkeakoulunkatu 10,
FI-33720 Tampere
Finland

Mailing address
PO Box 527, FI-33101 Tampere
Finland

Switchboard:
+358 3 311 511