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

TL;DR

This paper demonstrates a method to create high-Q coupled resonances on a silicon photonic crystal waveguide using a tapered nanofiber, achieving ultrahigh Q factors and high coupling efficiency with tunable resonances.

Contribution

The study introduces a novel approach for forming high-Q cavities at arbitrary positions on a photonic crystal waveguide using a tapered nanofiber contact, with tunable resonance and high coupling efficiency.

Findings

Achieved ultrahigh Q of 5.1 x 10^5 with 39% coupling efficiency.

Demonstrated tunable resonance wavelength by 27 pm via contact length adjustment.

Realized an all-pass filter coupled resonator system for potential slow light applications.

Abstract

We experimentally demonstrate high-Q cavity formation at an arbitrary position on a silicon photonic crystal waveguide by bringing a tapered nanofiber into contact with the surface of the slab. An ultrahigh Q of 5.1 x 10^5 is obtained with a coupling efficiency of 39%, whose resonant wavelength can be finely tuned by 27 pm by adjusting the contact length of the nanofiber. We also demonstrate an extremely high coupling efficiency of 99.6% with a loaded Q of 6.1 x 10^3. In addition, we show that we can obtain an all-pass filter type coupled resonator system, which has the potential to be used for slow light generation.