GHz Frequency Optical Pump-Probe (GFOPP) Metrology Tool for High Sensitivity Measurements of Acoustic Dissipation and Elastic Constants
Abstract
This request for research instrumentation is to support the purchase of the components needed to construct a flexible tool for measuring the fundamental acoustic properties of materials at microwave frequencies. Resonant vibrations of materials at audio frequencies are a part of our everyday experience. Musical instruments use acoustic resonances to define musical notes and rubbing the top of a wine glass causes the glass to sing a pure tone. At higher frequencies, from millions to billions of cycles per second (MHz to GHz), acoustic resonators support a surprising diversity of modern technologies from ultrasonic transducers for medical imaging to bulk-acousticwave filters that are used in cell-phones to separate a blue-tooth signal from a wi-fi signal. Acoustic resonators are also a critical component of emerging quantum devices with the potential of providing approaches to store and transmit quantum information. A key materials property for all of these applications is how quickly the energy stored in the vibrations of the resonators are dissipated into heat. A lower rate of dissipation generally increases the performance of a filter or sensor. Theories that describe the materials physics of acoustic dissipation were first developed 50 years ago but these equations have never been solved in general, and the solutions that are known are appropriate only for highly restrictive conditions on frequency and temperature. The limited progress in this area of science can be partially attributed to the lack of data that scientists and engineers can use to explore new ideas and motivate further advances in theory. Our new tool for studies of GHz frequency acoustics is designed to overcome the experimental limitations of past approaches that were mostly limited to bulk crystals of piezoelectric materials. Optical and electronic components used in high bandwidth transmission of information over optical fibers provide a cost-effective route to generate and detect the vibrations of acoustic resonators. Acoustic resonators will be fabricated using state-of-the-art facilities for synthesis, processing, and fabrication of materials in the Materials Research Laboratory at the University of Illinois. The power and convenience of the GHz frequency optical pump probe (GFOPP) metrology tool will enable measurements of a wide variety of materials in bulk and thin film form and will enable efficient exploration of the effects of composition, processing, and microstructure on acoustic dissipation. The new data will directly impact the design of new generations of acoustic resonators for signal processing and mass sensing; and will advance basic understanding of the ultimate limits to acoustic dissipation in materials.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 09, 2020
- Source ID
- W911NF2010067
Entities
People
- David Cahill
Organizations
- Army Contracting Command
- United States Army
- University of Illinois Urbana–Champaign