Integrated beam-steering optical sensor based on a self-rolled-up microtube resonator

Abstract

We propose and numerically demonstrate an integrated optical sensor that employs beam steering as a label-free detection mechanism. Although optical microcavities are well known for their high refractometric sensitivity, traditional implementations rely on wavelength interrogation, which requires bulky spectral analysis equipment and limits portability. To overcome this limitation, we introduce a compact sensor architecture consisting of a self-rolled-up microtube resonator integrated with a silicon waveguide and engineered with a periodic nanohole array. In this design, the whispering gallery mode interacts with the analyte and radiates into the far field as a directional beam. The sensor is capable of detecting both gases and liquids, exhibiting high angular sensitivities of 229.2 deg/RIU for gas-phase sensing and 203.2 deg/RIU for liquid-phase sensing. By eliminating the need for tunable lasers or optical spectrum analyzers, this platform provides a compact and cost-effective solution for next-generation point-of-care diagnostics and environmental monitoring.