Silica optical microwires—smaller than ordinary optical fibers and with potential applications in sensing, as single-photon sources, and for use in optical interconnects—are difficult to uniformly manufacture using bottom-up fabrication processes such as tapering down larger-diameter optical fibers. Fortunately, researchers at the University of Sydney (Sydney, Australia) and Université Paris Sud (Orsay, France) have recently accomplished self-assembly of silica microwire waveguides on hydrophilic glass slides using convective flow within an evaporating drop containing silica nanoparticles, all at room temperature. The development opens up the possibility of integrating any material into silica for the first time.
The researchers improved the self-assembly uniformity by demonstrating that alteration of the contact angle distribution around a solution droplet on a glass slide improves the uniformity of the microwires as the droplet is evaporated. To accomplish this reduced angle and create a more elliptical-vs.-spherical water droplet, application of an ultraviolet (UV) laser beam at 193 nm fine-tunes the interfacial solid-liquid interface around the droplet and alters its effective geometry. That is, the laser treatment transforms (in the small-drop-domain limit) a spherical caplet formed on a hydrophilic surface into a more ellipsoidal-like (angle on one side is different than the opposite side) form, which improves convective self-assembly of silica nanoparticles into microwires within the drop. Uniform microwires with diameters of tens of micrometers were demonstrated using the technique. Contact John Canning at [email protected].
Gail Overton | Senior Editor (2004-2020)
Gail has more than 30 years of engineering, marketing, product management, and editorial experience in the photonics and optical communications industry. Before joining the staff at Laser Focus World in 2004, she held many product management and product marketing roles in the fiber-optics industry, most notably at Hughes (El Segundo, CA), GTE Labs (Waltham, MA), Corning (Corning, NY), Photon Kinetics (Beaverton, OR), and Newport Corporation (Irvine, CA). During her marketing career, Gail published articles in WDM Solutions and Sensors magazine and traveled internationally to conduct product and sales training. Gail received her BS degree in physics, with an emphasis in optics, from San Diego State University in San Diego, CA in May 1986.