Low Index-Contrast Photonic Crystal Nanobeam Resonator Based on PMMA on Silica Substrate

The integrated photonics has been revolutionized by the development of photonic crystal cavities, which are essential for confining and controlling light at the wavelength scale. These structures are characterized by their ability to localize optical fields within a small mode volume V, and sustain them with a high-quality factor Q, a measure of optical energy storage. The Q/V ratio is a critical figure of merit, as it governs the strength of light–matter interactions, making such cavities indispensable for a wide range of applications. At the same time, polymers are a highly versatile class of materials for micro and nanofabrication. They have been actively used in photonics as they can be integrated and doped with a wide range of materials, providing structures with tunable photonic response. Thus, in this work the design of a one-dimensional polymeric photonic crystal resonator based on polymethyl-methacrylate and suspended in air, and placed on a silica substrate, is presented. Using the three-dimensional finite-difference time-domain method and deterministic high-Q design method, the polymeric photonic crystal cavity design and optimization are investigated theoretically. A high Q-factor of 5 × 105, small mode volume V of 0.81(λ/ncavity)3, and Purcell factor F of 4.7 × 104 for the suspended photonic crystal cavity at the resonant telecommunications wavelength of λ = 1.55 µm can be achieved. For the structure placed on a silica substrate a maximum Q-factor is 3 × 102, mode volume V is 0.88(λ/ncavity)3, and Purcell factor F is 26 at λ ~ 1.55 µm.