Group

Dr. ALAN D. BRISTOW (Group Leader)

Alan did his PhD work on the optical dispersion and nonlinear response of photonic crystal waveguides at the University of Sheffield. As a postdoctoral researcher, he worked on other nonlinear effects including sum- and difference-frequency conversion in photonics crystals, the nonlinear response of metals and metallodielectric heterostructures and the injection of photocurrents into unstrained and unbiased silicon. He also characterized the two-photon and Kerr refractive index of bulk silicon, which is hugely important for the implementation of silicon photonics. He subsequently worked on coherent control and spectroscopy of semiconductor nanostructures, developing a versatile platform for performing multidimensional coherent electronic spectroscopy.

Alan's current research goals include development of experimental tools for condensed matter physics and the exploration of coherent and nonlinear optical properties of photonic nanostructures and quantum materials. This work has included measurement of polaritons in semiconductor microcavity using two-dimensional coherent spectroscopy, the development of chalcopyrite crystals for broadband terahertz generation, mapping injection and shift currents in topological insulators, outlining the parameters for coherent charge induction on the surfaces of nanoparticles by plasmon-induced resonant energy transfer, and characterizing model systems for potential hot-carrier solar cells.

Graduate Students and Postdocs

HUNTER LOUSCHER (2023-present) - Hunter is working on mutidimensional coherent spectroscopy of biexcitons in semiconductor nanostrucutures in collaboration with the Nanoscale Spectroscopy Group at NIST.

SETH WOODWYK (2023-present) - Seth is working on the optical properties of low-temperature materials, including phonon-emitting superlattices and superconducting transition-edge sensors. These projects are in collaboration with Marshall University and NASA respectively. Seth is joint member of the Holcomb Interface Group.

Dr. GIUSEPPE FUMERO (2023-present) - Giuseppe did his PhD at Sapienza Università di Roma and works on mutidimensional coherent spectroscopy of nanostrucutures. He is based at NIST in the Nanoscale Spectroscopy Group working with Dr. Jared Wahlstrand.

HARRISON (HENRY) LOH (2021-present) - Henry is working on nano-printing methods of dielectrics and metals and the subsequent AC conductivity of those materials in device applications. Henry is an Engineering student working with Prof. Kostas Sierros.

SUNIL GYAWALI (2020-present) - Sunil is working on the charge carrier dynamics of Cu2O nano-catalysts to determine the mechanisms for charge separation and coherent properties associated with multiple Mie resonances within the nanoparticles. This work is performed in collaboration with the group of Prof. Mari Andiappan at Oklahoma State University.

Dr. JAGANNATH PAUL (2019-2022) - Jagannath did his PhD at University of South Florida and worked on coherent properties of exciton-polaritons in semiconductor microcavities. He was based at NIST in the Nanoscale Spectroscopy Group and departed for India in 2022.

Dr. HERATH (CHATHU) PIYATHILAKA (2016-2022) - Chathu measured the charge carrier dynamics and transport in type-II-aligned quantum well heterostructures, proposed as model systems for exploring hot-carrier extraction in order to overcome the detailed balance limit. Chath graduated in May 2022 to work a Intel Corp. His Ph.D. dissertation is titled Hot-carrier dynamics and transport mechanisms in InAs/AlAsSb multiple quantum wells.

Dr. RISHMALI SOORIYAGODA (2016-2021) - Rishmali worked on the charge dynamics of a range of nanostructured and bulk semiconductors for photonic and photocatalytic applications. She developed methods of determining the charge carrier transport in bulk materials as a function of temperature to obtain complementary mobility information to Hall-effect measurements, recorded without strong external magnetic fields. Rishmali graduated in August 2021 to become academic staff at Colombo University in Sri Lanka. Her Ph.D. dissertation is titled Equilibrium and non-equilibrium ultrafast carrier transport and dynamics in chalcopyrite semiconductors .

Dr. BRIAN WILMER (2011-2016) - Brian measured the detuning dependenc of exciton-polaritons in semiconductor microcavities using two-dimensional coherent spectroscopy. Additionally, he also explored the role of strain on excitons in bulk GaAs. Brian graduated in 2016 to work at an US Army research facility. His Ph.D. dissertation is titled Multidimensional coherent spectroscopy of GaAs excitons and quantum microcavity polaritons .

Dr. DEREK BAS (2011-2016) - Derek explored the photocurrents of topological insulators and terahertz interaction with antiferromagnetic magnons in bulk fluoride crystals. He graduate 2016 to work with the Air-Force Research Laboratory. His Ph.D. dissertation is titled Optical and terahertz measurements of spintronic materials.

Dr. SCOTT CUSHING (2011-2015) - Scott pioneered the mechanism of plasmon-induced resonance energy transfer (PIRET) in hybrid nanoparticles to improve catalysis. PIRET is a coherent oscillation in metallic nanoparticles that can induce charges at a dielectric surface and is therefore a specific subset of a broader class of Förster resonance energy transfer mechanisms. Scott graduated 2015 to become a postdoc at UC Berkeley before becoming a professor at Caltech. His Ph.D. dissertation is titled Plasmonic enhancement mechanisms in solar energy harvesting.

Dr. TESS OLIVER (2010-2015) - Tess spectroscopically explored the coupling of binder molecules to rare-earth-doped glasses as preparation fo biomarker attachment. She also explored charge carrier transfer dynamics in TiO2-CdSe nanoparticle-quantum dot heterostructures. Tess graduated 2015 to become a visiting professor at Wooster College, OH and was then employed by a regional chemical analysis company. Her Ph.D. dissertation is titled Optical spectroscopy of nanoscale and heterostructured oxides.

Dr. JOSEPH ROWLEY (2010-2013) - Joe worked on the generation of broadband terahertz radiation by optical rectification in ZnGeP2 crystals. He explored the generation strength, the polarization conditions and the details of the saturation of the emitted terahertz through nonlinear absorption. Joe graduated in 2013 to work at Intel Corp. His Ph.D. dissertation is titled Chalcopyrite semiconductors as sources for terahertz spectroscopy.

Undergraduate Students and Guests

The group has trained many undergraduates over the years, many of whom have gone on to graduate school nationally. We have also hosted several international guest researchers. If you are interested in joining the group please contact Alan.