Silicon-on-Insulator Microring Resonator Sensor Integrated on an Optical Fiber Facet

In recent years, portable, sensitive, and cheap sensors have gained interest in fields such as medical diagnostics, food quality control, environmental monitoring, and drug development. Especially optical sensors in silicon-on-insulator (SOI) have proven to be very promising, because they have a low limit of detection, are very compact, and can be made with cheap mass fabrication techniques. While a lot of progress has been made to implement such sensors in small and easy-to-use cartridges, many applications require a sensor probe that can perform measurements at locations that are hard to reach. We introduce a method to integrate an SOI photonic sensor on the facet of a standard single-mode optical fiber, and apply this method to a well-known ring resonator refractive index sensor without deteriorating its sensitivity. We thus combined the good performance of SOI sensors with the high mobility of optical fibers.