GOALI: Spatially selective phase transformations of glass to single crystal and electrically conducting 3D architectures

Lehigh University, Bethlehem PA

Investigators

Abstract

NON-TECHNICAL DESCRIPTION: Just as integrated circuit technology reduced the size, lowered the cost and made sophisticated electronic devices accessible to masses, a similar transformative impact is expected from the transition of 2D assembly of discrete optical elements on a surface to a 3D integrated optics platform, especially with ever increasing demand for information and data transmission. Manipulation of photons that require special transparent single crystals is inherently much more difficult, making integrated optics a persistent challenge vs. that of electrons that flow readily through any conducting wire. This industry-university collaborative project advances new fabrication methods for realizing optically active single crystal architecture in glass suitable for practical devices, while educating doctoral students through a novel Pasteur Partners PhD (P3) model. These students pursue use-inspired multidisciplinary research co-advised by a faculty and a company scientist, and acquire essential skills for successful careers in industry, academia, national labs, etc. TECHNICAL DETAILS: A working integrated ‘micro-optics chip’ would not be complete without optically active elements that are also accessible to receive an electrical signal. Such elements need to be high quality electro-optic single crystals incorporated within a circuit of waveguides. This project builds on the successful demonstration of ferroelectric single crystal architecture in glass (SCAG) which is constructed in 3D using femtosecond lasers. However, the optical loss of such SCAG waveguides has been too high. Often the SCAG formation is accompanied by a redistribution of elements between glass and crystal. Also, the lattice of SCAG is modified by the stresses resulting from change in density at the growth front during crystallization. Through a fundamental understanding of these features of crystal growth under the confinement by the surrounding glass, this project is reducing optical loss by creating a graded refractive index profile within the crystal. The desired variation of refractive index is introduced through dynamic control of temperature by a laser beam of appropriate intensity profile. In parallel, this project is pursuing formation of conducting paths by forming metallic nanoparticles or precipitates of a conducting oxide by fs laser irradiation. The project is introducing new methodologies for fabricating 3D crystal-in-glass metamaterials for a range of photonic and optoelectronic applications. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.