Strip-Loaded Nanophotonic Interfaces for Resonant Coupling and Single-Photon Routing

TL;DR

This paper presents the design and simulation of strip-loaded nanophotonic interfaces, including resonant cavities and directional couplers, to improve photon coupling, routing, and indistinguishability for quantum optical applications.

Contribution

It introduces a novel nanophotonic interface design with optimized mode confinement and high Q-factors, and compares photonic and plasmonic structures for efficient photon routing.

Findings

Achieved a cavity mode volume of approximately 7.0(rac{ ext{lambda}}{n})^3 with a Q-factor of 7000.

Simulated photon indistinguishability of 97% at 4K using the proposed cavity.

Compared photonic and plasmonic couplers, highlighting trade-offs in loss and bending radius.

Abstract

We report on the design and simulation of strip-loaded nanophotonic interfaces aimed at improving resonant coupling and photon routing efficiency. In our design, the guided mode is confined within a plane by a high-index thin film and is loosely confined laterally by a lower index strip. Using a hydrogen silsesquioxane (HSQ) strip, titanium dioxide core, and silicon dioxide substrate, we optimise the waveguide dimensions for maximum lateral confinement of light. Specifically, we propose a polymer-based Bragg grating cavity and ring resonator that achieve near-optimal mode volumes and high Q-factors. Our simulations suggest that a cavity with a mode volume of V_{\text{eff}} \approx 7.0 \left(\frac{\lambda}{n}\right)^3 and a Q-factor of 7000 can produce photons with 97% indistinguishability at 4K. Additionally, we investigate directional couplers for efficient photon routing, comparing photonic and plasmonic material structures. While pure photonic structures demonstrate lower loss and improved quality factors, they face practical limitations in terms of bending radius. Conversely, plasmonic structures offer shorter bending radii but higher propagation losses. This research lays the groundwork for future nanophotonic designs, aiming to enhance photon generation and routing capabilities for quantum optical applications.