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Mikko Närhi, Andrei Fedotov, Kseniia Aksenova, Julia Fiebrandt, Thomas Schönau, Mario Gerecke, and Regina Gumenyuk

We study numerically the possibility of using various gain-switched seed laser pulse parameters and fibers for a low-cost, all-fiber Mamyshev regenerator scheme. We find that for increasing pulse durations, sufficient spectral broadening will be difficult to achieve in practice and careful design of the system parameters is required for the regenerator to function. Furthermore, an optimal input peak power level can be defined for a given fiber and pulse duration that results from a balance of competing Kerr effect and stimulated Raman scattering. We also demonstrate experimental results of 3 ps pulse generation seeded by an 80 ps gain-switched diode. Our results pave the way for designing pulse-on-demand picosecond scale fiber sources for applications.

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George Flamourakis, Antonis Kordas, Georgios D. Barmparis, Anthi Ranella, Maria Farsari

Multiphoton lithography allows the high resolution, free-form 3D printing of structures such as micro-optical elements and 3D scaffolds for Tissue Engineering. A major obstacle in its application in these fields is material and structure autofluorescence. Existing photoresists promise near zero fluorescent in expense of poor mechanical properties, and low printing efficiency. Sudan Black B is a molecular quencher used as a dye for biological studies and as means of decreasing the autofluorescence of polymers. In our study we report the use of Sudan Black B as both a photoinitiator and as a post-fabrication treatment step, using the zirconium silicate SZ2080TM for the development of a non-fluorescent composite. We use this material for
the 3D printing of micro-optical elements, and meso-scale scaffolds for Mesenchymal Stem Cell cultures. Our results show the hybrid, made photosensitive with Sudan Black B, can be used for the fabrication of high resolution, highly transparent, autofluorescence-free microstructures.

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High-Power Ultrafast LaSErs using tapered double-clad fibre. Project Repository Journal Oct-20

R Gumenyuk and PULSE Consortium

A breakthrough concept in high-power industrial lasers. Laser technology continues to have an almost unlimited number of applications. Following widespread developments using continuous-wave lasers, breakthroughs in high-power short-pulsed lasers were recently recognised by the Nobel Prize in Physics 2018 to Gérard Mourou and Donna Strickland for their method of generating high-intensity, ultra-short optical pulses. Although, a relatively short time ago, the femtosecond laser was a tool consigned to the laboratory; now these systems have developed the reliability necessary for use in industry. Ultrafast pulsed lasers have seen exponential growth with the number of filed patents increasing five-fold from
about 100 to 500 per year (Mottay, 2013). Several advanced niche applications have benefited from fs-laser processing including in photonics (Misawa and Juodkazis, 2006), microelectronics (Rizvi, Karnakis and Gower, 2001), MEMS (Bellouard, 2011) and many other markets.

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Picosecond Yb-doped tapered fiber laser system with 1.26 MW peak power and 200 W average output power. Oct-20

Andrey Petrov, Maxim Odnoblyudov, Regina Gumenyuk, Lidiya Minyonok, Andrey Chumachenko & Valery Filippov 

We demonstrate a compact picosecond master-oscillator power-amplifier (MOPA) system based on an Yb-doped polarization-maintaining double-clad tapered fiber (T-DCF) delivering pulses with over 1.26 MW peak power and average output power up to 200 W preserving near diffraction limited beam quality. The unique properties of an active tapered fiber enable to amplify the seed pulses directly with no need for applying of additional stretching technique. This simplified laser system can find the practical implementation in industrial micromachining.

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Tornado waves. Optics Letters. Mar-20  

Apostolos Brimis, Konstantinos G. Makris, and Dimitris G. Papazoglou

We show that light spiraling like a tornado can be generated by superimposing abruptly auto-focusing ring-Airy beams that carry orbital angular momentum of opposite handedness. With different parabolic propagation trajectories, the superimposing ring-Airy beams are tailored to abruptly auto-focus at overlapping focal regions. This results in a complex wave with intense lobes that twist and shrink in an accelerating fashion along propagation. By achieving angular acceleration values that exceed 295  rad/mm2, these tornado waves can find numerous applications in laser trapping, direct laser writing, and high-harmonic generation.

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Short pulse generation from electrically pumped VECSELs (Invited Paper)SPIE Photonics West. Feb-20

N.B. Chichkov, A.V. Kovalev, A. Yadav, K.A. Fedorova, E.A. Viktorov, E.U. Rafailov

Passively mode-locked electrically-pumped (EP) VECSELs are compact, low-cost sources of picosecond laser pulses. Since the first demonstration of passive mode-locking in 2003, several different EP-VECSEL designs and mode-locking methods have been investigated. Mode-locking has enabled the generation of output pulses with durations of few picoseconds and peak powers of several Watts. In this publication, we review the state-of-the-art and ongoing research in the field of mode-locked EP-VECSEL. An overview of operation states, laser performance, and output pulse characteristics will be presented. Additionally, we will discuss laser designs, mode-locking techniques, and nonlinear pulse dynamics in mode-locked EP-VECSEL.

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Large-mode-area double clad ytterbium-doped tapered fiber with circular birefringence

Rissanen, J., Fedotov, A., Noronen, T., Gumenyuk, R., Chamorovskiy, Y., Kolosovskii, A., Voloshin, V., Vorobev, I., Odnoblyudov, M. & Filippov, M

We demonstrated, for the first time to our best knowledge, an active tapered double clad fiber with circular birefringence and 35 μm core diameter. The output radiation had perfect beam quality (M2=1.18/1.1) and linearly polarized light with 15 dB of PER. The developed double clad active fiber was investigated for amplification of picosecond pulses in allfiber MOPA system. The MOPA system delivered 50 ps pulses with 55 W of the average power revealed 34.4 dB gain of the booster amplifier.

The PULSE Consortium

We have produced a PULSE project flyer that provides an overview of the project, as well as it's aims, objectives and targets. Not only will this flyer be distributed at relevant conferences, demonstrations and trade fairs, but it is also available to download using the link below.

Download here!

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The PULSE Consortium

We have produced a PULSE project flyer that provides an overview of the project, as well as it's aims, objectives and targets. Not only will this flyer be distributed at relevant conferences, demonstrations and trade fairs, but it is also available to download using the link below.

Download here!

Leaflet front.png