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Birefringence in Injection-Molded Cyclic Olefin Copolymer Substrates and Its Impact on Integrated Photonic
Stefan Kefer1, Tobias Limbach1, Natalie Pape1
1Applied Laser and Photonics Group, Aschaffenburg University of Applied Sciences, Wuerzburger Strasse 45, 63743 Aschaffenburg, Germany.
Polymers
|January 23, 2024
Summary
Birefringence in cyclic olefin copolymer plates is unevenly distributed, impacting photonic devices. Burying structures deeper into the material can mitigate these effects for better performance.
Area of Science:
- Materials Science
- Optics
- Polymer Science
Background:
- Injection-molded cyclic olefin copolymers (COCs) are used in optical applications.
- Birefringence in polymers can significantly alter optical properties.
- Understanding and controlling birefringence is crucial for integrated photonic devices.
Purpose of the Study:
- To quantify birefringence in injection-molded COC plates.
- To investigate the impact of birefringence on mechanical and optical properties.
- To provide fabrication guidelines for integrated photonic structures in COCs.
Main Methods:
- Polarimetry and prism coupler used to examine anisotropy in 3D.
- Birefringence distribution analyzed across the COC plate.
- Optical performance of waveguides and Bragg gratings evaluated.
Main Results:
- Birefringence is inhomogeneously distributed, varying locally and with observation direction.
- Maximum birefringence of 10 × 10-4 found at the surface near the injection gate, decreasing with depth.
- Photonic structures exhibit orientation-dependent performance due to local birefringence.
Conclusions:
- Quantifying birefringence is essential for COC substrates in integrated photonics.
- Birefringence strongly affects near-surface photonic structures like waveguides and gratings.
- Burying photonic structures deeper in the COC can eliminate birefringence effects.
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