Fiber-based optofluidics

Abstract

Listen

Translate article

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.