Domestic research projects

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Research projects (co)funded by the Slovenian Research Agency.

 

  • Member of University of Ljubljana: UL Faculty of Mechanical Engineering
  • Project code: L2-8183
  • Project title: High power highly adaptable fiber lasers for the industrial applications
  • Period: 01.05.2017 - 30.04.2020
  • Range on year: 1,05 FTE
  • Head: doc. dr. Vid Agrež
  • Research activity: Engineering sciences and technologies 
  • Research Organisation: Link
  • Researchers: Link
  • Citations for bibliographic records: Link
Abstract:

Due to the directing of production technologies to mass production of custom-made products there is a need for precise and highly adaptable manufacturing systems. Such processes require laser processing systems that will enable fast (requires high power!) and precise spatial and temporal energy transfer to the workpiece. Modern high-power laser sources mostly meet the requirement of accurate spatial deployment very well, but not with regard to the timing and duration, especially in the case of high-speed processing that is typical for mass production. Such systems generally do not allow for very rapid changes in the parameters of the laser beam (output power, repetition frequency, pulse length), and consequently it is difficult to meet the requirement for a temporally precise transfer of energy.

Research carried out in the context of the proposed project will focus on the research and development of two completely new types of laser sources. The two new laser sources are based on an original design, which allows for high flexibility of the output parameters of the laser beam:

Highly adjustable fiber laser for macro-processing and for use in adaptive laser processing systems with output power in the range of several 100 W. The laser will be operating in continuous mode, in quasi-continuous mode with high frequency modulation in the range of 100 kHz and in pulse mode, with the possibility of generating any arbitrary sequence of laser pulses with high energy and high peak power, enabling precise energy input to the workpiece.

Highly adjustable fiber laser for the micro-processing with a completely adjustable pulse length (in the range from 10 ns to 1 s), a very wide range of the repetition frequency (from 1 Hz to several 10 MHz) and the average power in the range of several 100 W. It will be based on MOPA configuration with a specially controlled excitation source with two polarizations. Such a system will enable micro-processing at highest speed (over 1000 m/s).

Highly adjustable high-power laser will be based on gain switched ytterbium doped fiber laser. Until recently, it was considered that large average and peak powers cannot be easily achieved with gain switched one stage systems. Researchers of the project team have already shown that this type of lasers in spite of its simplicity provides many advantages over the classic design fiber and solid-state lasers. They showed that such lasers exhibit excellent stability of output power, regardless of the repetition of output pulses, and demonstrated record peak power (about 2 kW) and average power (about 40 W), which until now have not been exceeded. In order to reach the average power in the range of 1 kW it will be necessary to research and develop this type of laser completely from start. The concept is based on the modified temperature regime of the fiber laser operation, which will enable the achievement of significantly higher energies of individual laser pulses and enable efficient operation even in continuous mode. The key for the successful implementation is the new technology, which is mastered by a partner company Optacore. It is a specific active fiber manufacturing process, which allows operating the fiber at very high temperatures. Classical active optical fibers can operate up to a maximum of about 100 °C.

The entire project team has extensive knowledge and experience in the research field of new laser sources, as well as micro and macro processing. Both fields are covered by the researchers coming from academia and from the industry. This fact allows for organizing the project in such a way that there will be close collaboration between the researchers who will work on the research of the laser sources and the researchers who will work in the field of testing the use of lasers. In this way it will be possible to directly obtain feedback regarding the desired and optimal parameters of laser sources and thus greatly increase the effectiveness of the research.

The phases of the project and their realization:

WP1: Evaluation of the required laser parameters – testing of applications

Influence of pulsed and continuous operation at processing and testing of the applications.

WP2: Pulsed operation

Research of pulsed operation with the use of gain switching and temperature influence on the optimized laser system operation.

WP3: Active optical fiber

Research of optimized optical fiber and its development for operation at high temperatures.

WP4: Laser subsystems with the control systems

Research and development of lasers subsystems such as pump, seed, control electronics and cooling.

WP5: Laser resonator for CW and quasi CW high power laser source for micorprocessing.

Research of high power laser resonator optimization working at different driving conditions from continuous to pulsed operation.

WP6: Laser source with ultra-wide frequency range

Research on seed source for MOPA type fiber lasers and its combination with the preamplifier system.

 

The realization of the project is in the final phase of work packages.