Reversible Laser Imprinting of Phase Change Photonic Structures in Integrated Waveguides.

Area of Science:

• Materials Science
• Photonics
• Nanotechnology

Background:

• Laser-induced periodic surface structures (LIPSS) offer robust surface functionalization.
• Phase change materials (PCMs) enable rewritable LIPSS due to reversible phase modulation.
• Chalcogenide PCMs, like Ge2Sb2Te5 (GST), possess nonvolatility, optical contrast, and fast switching speeds.

Purpose of the Study:

• To explore phase change LIPSS formation in GST thin films integrated with waveguides.
• To investigate the control over LIPSS morphology (period, fill factor) via laser tuning.
• To assess the limitations of multicycle rewriting for these structures.

Main Methods:

• Fabrication of GST thin films on planar and rib waveguides.
• Laser irradiation to induce periodic surface structures.
• Morphological characterization and analysis of rewriting stability.

Main Results:

• Demonstrated controllable formation of phase change LIPSS in GST.
• Identified tuning parameters for LIPSS period and fill factor.
• Investigated multicycle rewriting stability and limitations.
• Showcased LIPSS formation on a 1D waveguide.

Conclusions:

• Phase change LIPSS in GST are a promising approach for tunable integrated photonic devices.
• The ability to control LIPSS morphology and rewriting offers flexibility in device design.
• Potential applications include tunable Bragg filters and light decoupling structures.