Hybrid organic/inorganic resonators for sensing and telecommunications applications

Abstract

Historically, integrated photonic devices have been fabricated from inorganic material systems, such as silicon, silicon nitride, silica and gallium arsenide. As a result of their inherently low material loss and compatibility with nanofabrication tools, high performance waveguides and resonant cavities have been demonstrated. However, to achieve many of the desired performance metrics, it is necessary to implement active stabilization systems. For example, as a result of the thermo-optic effect, the resonant wavelength of a microcavity will change with temperature, resulting in an unpredictable resonant wavelength without temperature stabilization. Therefore, new materials and material systems are desired. One approach is to combine the inorganic materials conventionally used in telecommunications with organic polymeric materials. These hybrid systems offer the ability to tune the optical and mechanical properties of the inorganic materials, achieving athermal or temperature-independent performance. Additionally, given the wide range of polymeric material available, new material systems with previously unrealized behavior are possible; for example, materials which mechanically respond to UV, humidity and specific chemicals. Using silica toroidal whispering gallery mode resonant cavities as the device platform, a series of hybrid organic/inorganic resonators were fabricated. Several different types of organic layers were studied, varying both the specific polymeric material and the deposition method. For example, polyisobutylene was coated on the devices using either a spin-coating method or a surface initiated cationic polymerization process. With the wide range of possible organic materials, many different devices have been fabricated, including athermal devices, humidity and bio/chemical sensors, and microlasers.