High-Q coupled resonances on a PhC waveguide using a tapered nanofiber with high coupling efficiency

Area of Science:

• Photonics
• Materials Science
• Nanotechnology

Background:

• Silicon photonic crystals offer unique light manipulation properties.
• Integrating high-Q cavities is crucial for advanced photonic devices.
• Precise control over cavity formation and coupling remains a challenge.

Purpose of the Study:

• To demonstrate a novel method for creating high-Q cavities on silicon photonic crystal waveguides.
• To achieve arbitrary positioning and precise tuning of cavity resonance.
• To explore the potential for slow light generation using coupled resonances.

Main Methods:

• Experimental demonstration of cavity formation by contacting a tapered nanofiber with a silicon photonic crystal slab waveguide.
• Characterization of Q factor, coupling efficiency, and resonant wavelength tuning.
• Analysis of coupled resonance phenomena.

Main Results:

• Achieved ultrahigh Q factor of 5.1 × 10^5 with 39% coupling efficiency.
• Demonstrated resonant wavelength tunability of 27 pm by adjusting nanofiber contact length.
• Obtained extremely high coupling efficiency of 99.6% with a loaded Q of 6.1 × 10^3.
• Observed coupled resonances with potential for slow light applications.

Conclusions:

• The tapered nanofiber contact method enables flexible and high-performance cavity formation on silicon photonic crystal waveguides.
• This technique offers precise control over resonant properties, facilitating tailored photonic device design.
• The demonstrated coupled resonances open avenues for developing novel slow light functionalities.