Optical characterisation of long‐period grating using liquid droplets on an electrowetting‐on‐dielectric platform

Abstract

This paper describes the use of digital electrowetting as a means of characterising and modifying the optical transmission properties of long period gratings (LPGs) fabricated in boron doped germanosilicate single mode fibres. An electrowetting based platform has been designed to move fluid droplets, of around 2 µL volume, along the main axis of the LPG fibre. The droplets make contact with the cladding over the grating region of the fibre. Optical measurements are presented illustrating the tuning of the optical resonance wavelength of an LPG as the droplet advances step-wise along the fibre cladding under electrowetting based actuation, and the increase of 53 % in the LPG tuning range achieved by side-polishing the grating section of the fibre.

Prediction of the contact angle of colloids and microfluids during electrowetting

“…Electrowetting is consequence of the change in thermodynamic of system by applying potential [2]. This process has gained much attention in recent years for application in modern technologies due to its capability for controlling the liquid motion in very low volume without the usage of any mechanical tools [3]. For instance, this process could be utilised in liquid lenses and lab‐on‐a‐chip systems.…”