Polarization manipulation

The optical properties of materials

In my group we study the properties of a wide range of materials, including wide band gap semiconductors, charge denisty wave materials and 2D materials. In particular, we are interested in creating new types of polariton modes, which have behaviour seen not in conventional materials. We are also interested in using infrared spectroscopic techniques to understand materials which support condensed matter states, such as charge denisty waves.

Image from grant

NSF Career - CAREER: Photonics in the Lowest Symmetry Crystals

Tuesday, March 21, 2023
In this project PI Folland will determine how certain classes of crystals can be used to control both direction, and orientation of light waves.
Image of Shear Polaritons

Research on Hyperbolic Shear Polaritons published in Nature

Wednesday, February 23, 2022
Shear phenomena in the infrared dielectric response of a monoclinic crystal are shown to unveil a new polariton class termed hyperbolic shear polariton that can emerge in any low-symmetry monoclinic or triclinic system
Cover for Advanced Materials

Hybrid Mid-Near Infrared Waveguides

Tuesday, March 23, 2021
In recent work published in Advanced Materials, us and collaborators at Vanderbilt show that both near infrared and mid-infrared light can be guided on a silicon chip by combining two different materials

Enhanced infrared optoelectronics

The concepts of nanophotonics can be directly appplied to the creation of infrared light sources and detectors. Current infrared technology only operates at well below room temperature, however nanophotonics allows us to make devices smaller and more efficient. Infrared detectors form the basis of thermal imaging, and can be applied in areas from defence to enviromental monitoring.

PhP detector concept

Perspective on new concepts for infrared optoelectronics

Wednesday, February 23, 2022
Here we discuss how a new generation of infrared optoelectronics could be realized leveraging surface phonon polaritons.
Schematic of a superstructure grating

Superstructure Emitters published in APL

Wednesday, April 7, 2021
Superstructure gratings tailor thermal emission
ACS Photonics Strong coupling

Vibrational sensing and strong coupling

One of the applications for nanophotonics is in the detection of small ammounts of biological toxins and molecules. In my group we use polaritons to enhance the coupling of light to the vibrations of different molecules. If pushed far enough, the cavity enters what is known as the strong coupling regieme, which can give rise to new behaviour from the molecules. 

GaN characterization

New ONR award to studying GaN using infrared spectroscopy

Friday, June 16, 2023
In this program we will understand the properties of defects and dopants in vertical GaN power electronics

Perspective on anisotropy in nanophotonics published in ACS Photonics

Thursday, March 17, 2022
Publication reviews the possibilities for low symmetry materials for next generation nanophotonics.
Inverse design of CdO emitters

Inverse Design for Tailored thermal emission published in Nature Materials

Thursday, October 21, 2021
Hawkeye 16-9


In my group we use micro- and nanofabriaction proecess in order to fabricate optical structures and devices. We use a combination of lithography, depsotion and transfer techniques in order to realize complex structures at the nanoscale. Above we show a micron scale Iowa logo, made used focussed ion beam lithography

FTIR schematic

Infrared Spectroscopy

In order to determine the properties of the materials we study we use infrared spectroscopy. This uses a Michelson Interferometer to measure the optical properties of materials from the near infrared through to the far infrared, encompassing the energies of crystal vibrations, intraband transitions in semiconductors, and semiconductor band gaps.