A refractive-index fiber sensor by using no-core fibers

Fiber optic nickel ion sensor based on direct ligand immobilization

“…NCF is a heterocore silica fiber with no cladding and an undoped core and has been previously reported for sensing applications [1,2] . The intermodal sensor is fabricated by splicing a 35mm length of nocore fiber (NCF) with a standard SMF fiber (Fig.…”

Chitosan-hydrogel-based fiber optic sensor for heavy metal ion detection

“…NCF is a pure silica fiber with an undoped core which has been used previously for refractive index sensing [1] . Sensor fabrication involved splicing a piece of NCF (40 mm) with SMFs to form an intermodal interferometer and the chitosan/PAA functionalization on the NCF surface was carried out through electrostatic self-assembly (ESA) process, as chitosan is cationic in acids and PAA is anionic due to the present of functional groups such as amine and carboxyl groups.…”

“…The interference of these modes leads to formation of self-images along the NCF [3]. The resultant spectral dip wavelength, λ N can be expressed by Equation (1), where N NCF is the effective refractive index at the core ambient interface, D NCF the core diameter of NCF, and L the length of NCF segment. From the equation, λ N is a function of N NCF , D NCF and L, since both D NCF and L can be regarded as a constant, λ N is only proportional to effective refractive index…”

Development of chitosan based optical fiber chemical sensors

“…NCF is a high-precision pure silica fiber with an undoped core and no cladding and has been widely utilized in the fabrication of heterocore structures for sensing of refractive index [75] and humidity [76]. The schematic diagram of the sensor is shown in Figure 3-3.…”

“…The histidine tagged protein sensor is implemented with a CS-Ni film functionalized NCF surface as the sensing element. The NCF is a cladding-less pure silica fiber with an undoped core and has previously been utilized for development of refractive index [75] and humidity sensors [76]. The sensing and reference arms are self contained within the NCF and have the same physical length but different optical path lengths due to modal dispersion [133].…”