Open AccessDielectrophoresis and colloidal phase transitions for ultra-broadband optical limiting
Author(s) -
Rittirong Nuansri,
Prathan Buranasiri,
H. Daniel Ou-Yang,
Ivan Biaggio
Publication year - 2019
Publication title -
optics letters/optics index
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.524
H-Index - 272
eISSN - 1071-2763
pISSN - 0146-9592
DOI - 10.1364/ol.44.003801
Subject(s) - materials science , optics , optical tweezers , colloid , phase (matter) , wavelength , polystyrene , polymer , optoelectronics , chemistry , physics , organic chemistry , composite material
We demonstrate wavelength-independent optical limiting based on colloidal phase transitions induced by the dielectrophoretic force from focused electromagnetic radiation. The focused radiation acts as an optical trap that increases the particle density. The increased density then leads to a colloidal gas-solid phase transition and an aggregate that effectively blocks the incoming radiation when it passes a threshold power. The process is reversible, with the colloidal particles returning to a homogenous distribution after the incoming radiation is removed. We demonstrate the effect using polystyrene nanoparticles mixed with pluronics and polyethylene glycol polymers in low-concentration KCl salt solutions. We observe the light-induced phase separation under confocal fluorescent microscope, and we provide a proof-of-principle demonstration of optical limiting using a 100 μm thick colloid cell.