Light and Capillary Waves Propagation in Water Fibers

Abstract

The confinement of light and sound, while they are traveling in fibers, enables a variety of light-matter interactions. Therefore, it is natural to ask if fibers can also host capillary waves. Capillary waves are similar to those we see when throwing a stone into a puddle. Such capillary waves are prohibited in microfluidic devices where the liquid is bounded by solid walls. In contrast, we have fabricated fibers, which are made entirely from water and are suspended in air. The water fiber can therefore move, e.g. in a resonant mode that reassembles the motion of a guitar string. In our experiment, light guided through the water fiber allows optical interrogation of is capillary oscillations. Co-confining two important oscillations in nature: capillary and electromagnetic, might allow a new type of devices called Micro-Electro-Capillary-Systems [MECS]. The softness of MECS is a million times higher when compared to what the current solid-based technology permits, which accordingly improves MECS response to minute forces such as small changes in acceleration. Additionally, MECS might allow new ways to optically interrogate viscosity and surface tension, as well as their changes caused by introducing an analyte into the system.

Waveguide-based chemo- and biosensors: complex emulsions for the detection of caffeine and proteins

“…20 However, in these approaches, high concentrations of analytes are required to obtain detectable signals within the small penetration depth of the evanescent field. More recently, significant advancements have been made in the development of new refractive index sensing device technologies, including plasmonic resonators, 21,22 spiral waveguides, 23 optical fibers, [24][25][26] and resonant microcavities. [27][28][29] These devices have been shown to impart exceptional sensitivity, yet, practical applications are hindered by complications including a challenging replication of robust instrumental platforms, incapability to produce realtime and multiplexed signals, or expensive and complicated manufacturing.…”

Engineered entropic forces allow ultrastrong dynamical backaction

“…Early work by Ashkin and Dziedzic (52) used radiation pressure from a focussed laser beam to deform an air-liquid interface, using the direction of the deflection (outward) to answer open questions about the momentum of photons in a dielectric. The malleability of liquid-liquid and liquid-air interfaces has also been leveraged in optofluidic devices such as adaptive lenses and "labon-chip" applications (53), as well as for fluidic optomechanical resonators (54)(55)(56), the generation of giant optical nonlinearities (57), and transformable optical cavities (30)-which have been proposed to reach the single-photon nonlinear regime (31). With the thick (d = 24 nm) film considered here, the van der Waals pressure P vdW ¼ ρα vdw d 3 , which opposes surface deformation and plays the role of the Young's modulus in a solid, is two billion times softer than the underlying silica sphere (40).…”

Cavity continuum

“…In toroids, level-crossing phenomena were fluorescently photographed [56], and in liquids droplets, fluorescent mapping resolved the structure of droplets whispering gallery modes [57], as well as of the fluidic vortices [58] they generate. In a similar manner, the optical modes of a water fiber were mapped [59]. Later on, modes of a few-droplet ensemble [19] were fluorescently mapped.…”