Silicon subwavelength grating waveguides with high-index chalcogenide glass cladding

Area of Science:

• Integrated photonics
• Nanophotonics
• Materials science

Background:

• Silicon subwavelength grating (SWG) waveguides allow precise control over light propagation through nanoscale refractive index engineering.
• Integrating diverse materials with silicon photonics platforms is crucial for expanding device functionality.

Purpose of the Study:

• To investigate the waveguiding properties of silicon SWG waveguides with a high-index chalcogenide glass top cladding.
• To demonstrate the fabrication and characterization of a hybrid SWG waveguide microring resonator.
• To explore the potential for athermal operation and improved light-matter interactions.

Main Methods:

• Analytical and numerical simulations were employed to study the heterogeneous SWG waveguide.
• Microring resonators were designed, fabricated, and characterized using an Arsenic trisulfide (As20S80) cladding.
• Thermal-optic properties were analyzed by measuring resonance shifts with temperature changes.

Main Results:

• The hybrid SWG waveguide with As20S80 cladding exhibited modified waveguiding behavior.
• A near athermal operation was achieved, with a minimum thermally induced resonance shift of -1.54 pm/K.
• Thermal reflow of the chalcogenide glass successfully eliminated air gaps, creating a conformal structure.

Conclusions:

• Combining silicon SWG waveguides with high-index chalcogenide glass provides a new design avenue for integrated photonics.
• The demonstrated hybrid structures show potential for modal confinement engineering and controlling light-matter interactions.
• These waveguides are suitable for applications in reconfigurable photonics, nonlinear optics, metamaterials, and slow light devices.