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3D diffractive elements through fs-laser direct writing

Direct laser writing using ultra-short pulsed lasers is an increasingly used technology for the generation of embedded photonic structures such as waveguides or holographic data storage. One underlying fundamental process is the controlled refractive index change of transparent dielectrics by laser irradiation.

In a collaboration with the Institute of Photonic technologies at the Friedrich Alexander University of Erlangen-Nürnberg (Prof. Michael Schmidt), we are investigating novel ways of generating aperiodic microstructures such as 3D computer-generated holograms. The focus of the team in Erlangen lies on the fabrication processes while the team in Innsbruck concentrates on element design and optical characterization using diffraction tomography.


Figure 1: widefield images of continuous (top) and segmented fs-laser written waveguides inside fused silica.

 Figure 2: Aperiodic Photonic Volume Elements can be computer generated and directly written into glass. They measure only about 0.1 x 0.1 x 2 mm³. Left: APVE for shaping arbitrary light fields; Right: APVE for spatial mode multiplexing; the outputs of six single mode fibers are coupled into an APVE, which shapes them into co-axially propagating HG modes. Such a mode multiplexing could increase data transfer rates in optical fiber communications.

 

 

Researchers on this project at our institute:

  • Simon Moser, MSc.
  • Alexander Jesacher, PhD (PI)

Funding

“3D diffractive elements through fs-laser direct writing” FWF I 3984,  2020 – 2023.

Collaborations

  • Michael Schmidt, LPT, Friedrich-Alexander University of Erlangen-Nürnberg, D
  • Martin Booth, Dept. of Engineering Science, University of Oxford, UK
  • Patrick Salter, Dept. of Engineering Science, University of Oxford, UK

Publications

[1] Martin Bawart, Molly A. May, Thomas Öttl, Clemens Roider, Stefan Bernet, Michael Schmidt, Monika Ritsch-Marte, and Alexander Jesacher, "Diffractive tunable lens for remote focusing in high-NA optical systems," Opt. Express 28, 26336-26347 (2020)

[2] Barré N., R. Shivaraman, L. Ackermann, S. Moser, M. Schmidt, P. Salter, M. Booth and A. Jesacher: Tomographic refractive index profiling of direct laser written waveguides. Optics Express 29, 22, 35414-35425, 2021, https://doi.org/10.1364/OE.434846

[3] Barré N. and A. Jesacher: Holographic beam shaping of partially coherent light. Optics Letters 47, 2, 425-428 (2022), https://doi.org/10.1364/OL.444074

[4] Barré N., Shivaraman R., Moser S, Salter P.,Schmidt M., Booth M.J., Jesacher A., Direct laser-written aperiodic photonic volume elements for complex light shaping with high efficiency: inverse design and fabrication, Adv. Photon. Nexus 2(3) 036006 (20 April 2023) https://doi.org/10.1117/1.APN.2.3.036006

Research