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Photosensitization agents for fs laser writing in PDMS
Jean-Sebastien Boisvert1, Antsar Hlil2,3,4, Sebastien Loranger5
1Department of Engineering Physics, Fabulas Laboratory, École Polytechnique Montréal, 2900 Édouard-Montpetit, Montreal, QC, H3T 1J4, Canada. jean-sebastien-2.boisvert@polymtl.ca.
Organic and organo-metallic compounds incorporated into Polydimethylsiloxane (PDMS) significantly enhance refractive index change under fs laser. Benzophenone and Irgacure-184 show high photosensitivity, with a synergistic effect observed in Bp+Ge mixtures for photonic device fabrication.
Area of Science:
- Materials Science
- Optics and Photonics
- Laser Physics
Background:
- Polydimethylsiloxane (PDMS) is a versatile soft polymer host for optical applications.
- Fabricating waveguides and photonic devices in PDMS requires materials with significant refractive index change under laser irradiation.
- Identifying suitable photosensitive compounds is crucial for advanced optical device manufacturing.
Purpose of the Study:
- To identify compounds that induce substantial refractive index changes in PDMS upon femtosecond (fs) laser exposure.
- To optimize the writing process for waveguides and photonic devices in PDMS by understanding material responses.
- To evaluate the photosensitivity of various inorganic and organic compounds, including Germanium, Titanium, Zirconium, Benzophenone, and Irgacure derivatives.
Main Methods:
- Incorporation of various inorganic (Germanium, Titania, Zirconite derivatives) and organic (Benzophenone, Irgacure 184/500/1173, 2959) compounds into PDMS.
- Systematic investigation of refractive index (RI) change under fs laser irradiation.
- Mapping RI change as a function of writing speed (1-40 mm/s), repetition rate (606-101 kHz), and number of passes (1-8).
- Quantitative analysis of photosensitivity and comparison between different material compositions.
Main Results:
- Organic compounds, specifically Irgacure-184 and Benzophenone (Bp), demonstrated the highest refractive index change (Δn ~ 10⁻²).
- A novel mixture of organic (Benzophenone) and organo-metallic (Germanium) materials (Bp+Ge) exhibited the strongest photosensitivity.
- A synergistic effect was observed in the Bp+Ge mixture, enhancing the overall photosensitivity of the PDMS host.
Conclusions:
- Organic compounds like Benzophenone and Irgacure-184 are highly effective for inducing refractive index changes in PDMS for photonic applications.
- The Bp+Ge mixture represents a promising novel material composition for advanced laser writing of optical devices in PDMS due to synergistic photosensitivity.
- Quantitative parameters established in this study enable informed selection of materials and processing conditions for optimal waveguide fabrication.
