Improving the sensing capabilities of miniaturized probes nanofabricated on the tip of optical fibers is crucial for a large number of sensing applications in remote and harsh environ-ments. While most research efforts are directed towards developing improved fabrications techniques or more sensitive structures, we show that the performance of these sensors can be significantly enhanced by designing an appropriate interrogation strategy. In our scheme, a nanostructured plasmonic fiber probe is included in an optical fiber resonator and interrogated with a single-mode laser. A wavelength shift of the plasmonic resonance generates a mismatch of the resonator optical impedance, which is monitored and actively compensated by an optoelectronic gain element. We characterize the technique using samples with different refractive index and compare its performance to a conventional sensing scheme. Our cavity-enhanced configuration leads to a 50-fold improvement of the probe’s refractive index resolution (corresponding to a detection limit of 10⁻⁵ RIU, the lowest reported so far for this type of sensors). The demonstrated measurement scheme can be devised with any fiber-optic sensor that responds with a resonance shift or with an attenuation of the transmitted/reflected intensity.

对于在偏远和恶劣环境中的大量传感应用而言，提高光纤尖端上纳米加工的微型探针的传感能力至关重要。虽然大多数研究工作都是针对开发改进的制造技术或更敏感的结构，但我们表明，通过设计适当的询问策略，可以显着提高这些传感器的性能。在我们的方案中，纳米结构的等离激元光纤探针包含在光纤谐振器中，并通过单模激光器进行询问。等离子体共振的波长偏移产生共振器光学阻抗的失配，该失配由光电增益元件监视并主动补偿。我们使用具有不同折射率的样本来表征该技术，并将其性能与常规传感方案进行比较。我们的腔增强配置使探头的折射率分辨率提高了50倍（对应于10的检测极限）⁻⁵ RIU，是迄今为止此类传感器报告的最低值）。可以使用任何以共振位移或透射/反射强度衰减做出响应的光纤传感器来设计所证明的测量方案。