Single-mode and single-polarization photonics with anchored-membrane waveguides

Area of Science:

• Integrated photonics
• Optoelectronic devices
• Materials science

Background:

• Existing membrane-type photonic structures suffer from instability and limited bandwidth.
• High index contrast and air-clad designs are desirable for advanced photonic integrated circuits.
• Achieving single-mode, single-polarization (SMSP) operation over broad spectral ranges remains a challenge.

Purpose of the Study:

• To propose and investigate a novel integrated photonic platform, the T-Guide, based on "anchored-membrane" structures.
• To demonstrate the feasibility of achieving unprecedented bandwidths for SMSP operation.
• To explore the potential of T-Guides for nonlinear photonic applications.

Main Methods:

• Numerical investigation using modal simulations.
• Fabrication of silicon T-Guide structures.
• Experimental characterization including cut-back loss measurements.

Main Results:

• The T-Guide platform exhibits compact, high index contrast, and stable "anchored-membrane" structures.
• SMSP operation over a 2.75-octave bandwidth (1.2–8.1 μm) was numerically demonstrated for silicon T-Guides.
• Broad regions of anomalous group velocity dispersion were engineered.
• Fabricated silicon T-Guides showed low propagation losses of 1.75 ± 0.3 dB/cm at 3.64 μm.

Conclusions:

• The T-Guide is a highly stable and versatile integrated photonic platform.
• Its ability to support SMSP operation over ultra-wide bandwidths makes it suitable for diverse photonic applications.
• The engineered dispersion properties position T-Guides as a promising platform for nonlinear optics and frequency conversion.