Optofluidics: a novel generation of reconfigurable and adaptive compact architectures

Abstract

The integration of microfluidics and microphotonics brings the ability to tune and reconfigure ultracompact optical devices. This flexibility is essentially provided by three characteristics of fluids that are scalable at the micron-scale: fluid mobility, large ranges of index modulation, and abrupt interfaces that can be easily reshaped. Several examples of optofluidic devices are presented here to illustrate the achievement of flexible devices on (semi) planar and compact platforms. First, we report an integrated geometry for a compact and tunable interferometer that exploits a sharp and mobile air/water interface. We then describe a class of optically controlled devices that rely on the actuation of optically trapped micron-sized objects within a fluid environment. The last architecture results from the infiltration of photonic crystal devices with fluids. This produces tunable and reconfigurable photonic devices, like optical switches. Higher degrees of functionality could be achieved with sophisticated optofluidic platforms that associate complex microfluidic delivery and mixing schemes with microphotonic devices. Moreover, optofluidics offers new opportunities for realizing highly responsive and compact sensors.

Laser microfluidics: fluid actuation by light

“…As a preliminary conclusion, the present survey illustrates another step in the exploration of the coupling between optics and microfluidics. Associated to much more exhaustive reviews [16,17,18] and to the increasing number of publications in this domain, it illustrates the emergence of a new and very active research field. In fact, the development of optofluidics, and in our case optohydrodynamics, is obviously in its infancy, probably because it intimately mixes disciplines which have been considered far away for a long time.…”

“…Parallel actuation was also demonstrated [15]. Moreover, the combination of optics and microfluidics, called optofluidics [16,17,18], also became an emergent research field offering an unprecedented level of integration for building a new generation of optically-actuated microdevices merging optical reconfigurability, softness of fluid, smoothness of fluid interfaces, and compactness. Along this line, great achievements were realized in optical switching [19] and splitting [20], adaptive lensing [21,22], interferometry [23], and lasing [24].…”

Optofluidics: a new tool for sensing

“…Recently a new class of highly compact single-beam microfluidic Mach-Zehnder interferometer has been demonstrated. In these devices the phase differences has been introduced by propagating a beam across a fluid/air discontinuity [33]. Typically, guided optic based interferometers are based on Mach-Zehnder configuration because it avoids the need of optical mirrors.…”

Reconfigurable photonic crystal circuits

“…The reconfigurability aspect offered by the fusion of microfluidics with photonic devices optofluidics [45][46][47][48][49] seems particularly well-suited to achieve such dynamic optical functions and has already received a great deal of research interest in recent years. Following K. Busch et al's suggestion to infiltrate a PhC structure wih electro-optics liquid crystals to expand the degree of tunability of PhCs [50], several works combining liquids and PhC microphotonics have been reported.…”