Optofluidics is the combination of photonic and microfluidic technologies to achieve enhanced functionality and
compactness in devices with applications in sensing, chemistry, biomedical engineering, photonic devices and
fundamental microfluidics research. Such a broad definition of the field lends itself many embodiments. Fiber optics
provides a unique and versatile platform for building optofluidic devices. Optical fibers can be used not only in their
traditional role, acting as a high quality waveguide for delivering light to an optofluidic device. Microstructured optical
fibers and the voids that constitute them can provide a home for the fluid phase. Photonic crystal fibers, for example,
can be filled with fluids to change the band gap properties of the fiber. The use of the fluid phase to tune photonic
structures has several benefits. The fluid phase is inherently mobile allowing the tuning medium to be dynamically
reconfigured through any connected aperture of the device. The nature of the fluid can also be adjusted through its
chemistry, allowing for a very broad range of optical properties thus further enhancing tunability. Very high refractive
index contrasts can be obtained between the fluid phase and the surrounding air, which can lead to great compactness in
interferometric devices and novel, tunable, interferometric structures such as the single beam interferometer presented
here. One of the great utilities of optofluidic devices is that where a photonic structure is tuned using microfluidics, the
same structure can be used in reverse, where a photonic structure is exposed to an unknown fluid and can act as a sensor.
A fiber Fabry-Perot is utilized here to measure the concentration of saline.