Towards practical liquid and gas sensing with photonic crystal fibres: side access to the fibre microstructure and single-mode liquid-core fibre

Abstract

Photonic crystal fibres (PCFs) have important applications in sensing the optical properties of fluids. To this end, the material should be inserted into the fibre holes in order to interact with the propagating field. When dealing with liquids, it is particularly interesting to exclusively insert the sample into the core of a hollow-core PCF, which then guides light through the liquid via total internal reflection. Nevertheless, there is still a series of issues to be addressed before fluid sensing with PCFs becomes practical. The work described here proposes and demonstrates possible solutions for two of these issues: (a) how to insert the sample through a lateral access to the fibre longitudinal holes so that the fibre tips are free for optical handling and accessing and (b) in the case of a liquid-core PCF, how to reduce the number of propagating modes.

Optical Fibres for Distributed Corrosion Sensing - Architecture and Characterisation

“…To overcome this, fabrication techniques that expose the core have been demonstrated by micro-machining fluidic side-channels at several locations along the fibre length [21][22][23][24], which results in short exposed regions in the order of tens of microns. This provides access to the core by the analyte, making it useful for real time sensing applications, but is still not practical for distributed sensing applications where long lengths are required.…”

Silica exposed-core microstructured optical fibers

“…This makes their use impossible for real time or distributed sensing applications and difficulty still exists when attempting to ensure stable optical coupling while filling. To overcome these problems, fabrication techniques which expose the core [24] have been demonstrated by micro-machining fluidic side-channels at several locations along the fiber length [25][26][27][28], which results in short exposed regions in the order of tens of microns. This provides access to the core by the analyte, making it useful for real time sensing applications.…”

Exposed-core microstructured optical fibers for real-time fluorescence sensing

“…The exposed-core fiber was first proposed in 2003 by Hoo et al [10] and fabrication has since been demonstrated by the use of a fusion splicer and air pressure to blow holes within an MOF [12], use of a focused ion beam [13,14], and femtosecond laser micromachining [15,16]. Also, tapering of MOFs can allow access to the guided optical field [17].…”