טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentDouvidzon Mark
SubjectLiquid-Walled Photonics
DepartmentDepartment of Nanoscience and Nanotechnology
Supervisor Professor Tal Carmon
Full Thesis textFull thesis text - English Version


Abstract

The confinement of light and sound enables a variety of light-matter interactions.

Therefore, it is natural to ask if optical devices 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 most microfluidic devices where the liquid is bounded by solid walls. In contrast, we have fabricated two optical devices which are not bounded by any solid: 1) An optical fiber made entirely out of water hanging in air and 2) an ultra-soft micro-resonator submerged in water.

As for the water fiber: It can move in a resonant mode that reassembles the motion

of a guitar string but with restoring forces related to surface tension at the liquid/air

boundary and not to the solid elasticity. In our experiment, light guided through

the water fiber allows optical interrogation of is capillary oscillations. We report its

fundamental oscillations and three higher harmonics. The softness of the water fiber

is a million times higher when compared to what the current solid-based technology

permits, which accordingly improves its deformation by minute forces, such as small

changes in acceleration.

As for the ultra-soft micro-resonator: We use oil in water and reduce its interfacial

tension by another million times in comparison to the already soft water fiber. Our

resonator is in fact so soft, that we are limited by the Brownian motion, which breaks

our device. At this softness we can deform the resonator at will with optical tweezers

while coupling light into it through an optical tapered fiber. We report six asymmetrically deformed optical cavities, the associated mode split, mode mapping and direct light emission.

Additionally, we developed a method to measure the capillary amplitude, resonance

spectrum, and damping of the deformed droplet. 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 106 − 1012 times higher when compared to what the current solid-based technology permits. 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