Novel Long Period Gratings in Channeled Optical Fibers

Here we report about the development of a fiber optic based microfluidic sensor. It is based on a single-mode fiber having two micro-channels with a diameter of 28 μm, usually referred to as side-hole fiber (SHF). The setup for providing the fiber with both optical connection and access to the micro-channels for input/output of liquid solutions was developed. Moreover, to probe the refractive index of the substance inside the micro-channels, a long period grating (LPG) transducer was written in the SHF by electric arc discharge technique. Testing was conducted by using distilled water inside the channels, demonstrating the possibility to detect the presence of a liquid rapidly and consuming low sample volumes through the LPG response. This device can find application for bio-chemical sensing.