Unconventional Methods for the Miniaturization of Three-dimensional Structures and Photonics Devices


Tommaso Baldacchini, Ph.D.
Division of Engineering and Applied Sciences

Location: Computer Science (CS), Room 174

Two new methods for the fabrication of micro and nanostructures will be described. In the first one, a non-linear optical process is used to prepare three-dimensional microstructures with complex geometries from photosensitive resins. This method uses laser pulses whose photon energy is too small to excite the initiator in a photopolymer by conventional one-photon absorption. When the beam is tightly focused with an objective of high magnification, however, the peak intensity in a small volume near the focal region is sufficient to initiate polymerization by the simultaneous absorption of two photons. By scanning the focal volume in all dimensions, one can fabricate three-dimensional structures with pinpoint accuracy.
In the second method, a two-step drawing process is used for the fabrication of silica wires with diameters down to 50 nm and lengths up to tens of millimeters. Scanning electron microscope images shows that these silica wires have excellent diameter uniformity and atomic-level smoothness, Light can be launched into these wires by optical evanescent coupling and low optical losses over a range of wavelengths from the visible to near-infrared are observed. Furthermore, these wires can be bent sharply without incurring large bending losses because of the large refractive index contrast between silica and air.