Junior Faculty Spotlight: Josh Caldwell
I joined the Mechanical Engineering Faculty at Vanderbilt University in May 2017, moving here from the US Naval Research Lab where I had been for the past 12 years. I joined as a tenured Associate Professor, with affiliated status in the Dept. of Electrical Engineering. I received by Bachelor’s I Chemistry from Virginia Tech in 2000, followed by my Ph.D. in Physical Chemistry in 2004 from the University of Florida. My research is focused on identifying materials that can interact with long-wavelength infrared light at nanoscale dimensions, enabling compact optical components, such as sources, lenses and detectors. This could provide the opportunity for on-chip photonics which are highly desirable for applications such as free-space communications or optical computations as well as providing avenues for IR beacons and sources for environmental and medical diagnostics as well as search and rescue.
Infrared spectroscopic and imaging techniques are widely implemented for non-contact measurements of temperatures, chemical identification and medical diagnostics, astronomical studies, and due to atmospheric windows in the 3-5 and 8-12 µm spectral ranges for thermal radiative cooling, free-space communications. In the visible spectral range there is a broad range of materials that offer ideal performance and due to the short wavelengths of light compact optical components, in the infrared, the materials of choice tend to have significant issues such as low transmission, high expense, high reactivity in ambient conditions and/or being very brittle. Furthermore, the long free-space wavelengths mean optical components must be significantly larger. Polaritons, which are quasi-particles of oscillating charges with light (photons), provide the means to circumvent the limitations of these long-wavelengths in the IR and focus the light to nanoscale dimensions. However, identifying the appropriate materials and device concepts that can suitably overcome these limitations is at the heart of my research.