Fiber and Integrated Waveguide‐Based Optical Sensors

Over the last years, a large part of the activity in applied photonics and especially in fiber or integrated waveguide-based devices has been transferred partially from the photonics telecommunications industry towards the optical sensors research. Further to the necessity due to telecommunications sector turn down, it has been proven that this shift has been welcomed by the development in relevant industrial sectors (pharmaceutical, medical) where new requirements for very accurate control of the manufacturing process are required. This increasing research effort on all-optical sensors’ technology, combined with emerging and demanding applications, has demonstrated a promising technological platform characterized by unique sensitivity, compactness, reliability, electromagnetic immunity, and low cost, promoting them to a preferable solution for real-world applications, from mechanical sensing to chemical/biochemical and pharmaceutical industry. The inherent also capability of photonics technology for the efficient sensing-signal transmission through optical fibers suggests an enhanced functionality from a system’s perspective, by enabling the high-speed interconnection of multiple remote sensing points, either through a single readout and administration unit, or through a distributed network. Furthermore the need for development of large-scale ad hoc sensor networks requires reliable autonomous and controllable sensing nodes and optical sensors exhibit very attractive and unique characteristics to play key role in this area. Emerging technologies combining new design concepts and operational approaches such as microstructured fibers (PCFs), tapered nanofibers, Bragg gratings, and long-period gratings, interferometric devices, as well as Surface Plasmon Resonance (SPR) devices have shown a strong impetus for novel applications. A critical issue which could dramatically enhance the performance of such functional devices is the use of novel polymers and nanostructured materials able to improve the sensitivity and expand also sensors selectivity range.