Nanophotonics and Optoelectronics

At the nanoscale, materials exhibit optical and electronic behaviors that differ from their bulk counterparts. In our lab, we focus on two material platforms that are especially promising for next-generation optoelectronics: two-dimensional (2D) materials and plasmonic nanostructures. These systems allow light to be confined, guided, and modulated at extremely small length scales, contributing to ongoing advances in the broader field of nanophotonics and enabling device concepts not possible in conventional materials.

When gold is structured into nanoparticles or nanostructured films, it supports surface plasmon resonances—collective oscillations of conduction electrons driven by light. These resonances enable deep sub-wavelength light confinement, concentrating electromagnetic fields into volumes far smaller than the wavelength of light. This extreme field enhancement opens pathways for applications in biosensing, photodetection and nonlinear optics, to name a few.

Similarly, 2D materials benefit from strong quantum confinement and reduced dielectric screening, giving rise to unique properties such as high carrier mobilities, tunable optical responses and strong excitonic effects even at room temperature. These characteristics make them natural candidates for next-generation optoelectronic devices. For instance, graphene enables ultrafast photodetection due to its gapless electronic structure and extremely fast carrier dynamics, while transition metal dichalcogenides (TMDCs) exhibit strong excitonic emission, making them promising for light sources, optical modulators, and single-photon devices.

Our lab’s research focuses on combining 2D materials with nanophotonic architectures to confine, guide, and control light at the nanometer scale. By integrating atomically thin materials with carefully engineered optical resonators and metasurfaces, or by directly patterning the 2D materials into the resonant structures themselves, we seek to engineer light–matter interactions, unlock new regimes of nonlinear and excitonic physics and enable novel device concepts. We also stack 2D layers into van der Waals heterostructures to tailor the local optical environment, engineer interlayer coupling and build complex device platforms from atomically thin components which can be seamlessly integrated with nanophotonic structures. Through these efforts, we build the foundation for advanced optoelectronic and hybrid quantum systems.

Device Design and Modeling

Every design in our lab begins with calculating the properties we aim to achieve. To do this, we use multiphysics solvers such as COMSOL and FDTD Solutions, building models that predict quantities like electromagnetic field distributions, reflection/absorption spectra, emission behavior, electrostatics and etc. We then compare these simulations with experimental measurements and refine the models to capture the underlying physics more accurately. This continuous feedback loop between theory and experiment enables rapid iteration and accelerates the development of new nanophotonic and device concepts. By optimizing devices in simulation before fabrication, we significantly reduce design cycles and achieve higher performance in our final prototypes.

2D/Nanophotonics Integration

After the design and simulation stage, we move to device fabrication. We pattern nanophotonic structures using electron-beam lithography (EBL) and verify their geometry and surface quality with SEM and AFM. We also characterize their optical response using dark-field spectroscopy and FTIR measurements to confirm resonance wavelengths and optical properties. Once the nanostructures are validated, we integrate them with 2D materials. Because these materials are held together by van der Waals forces rather than chemical bonds, they can be cleanly lifted and transferred onto the nanophotonic structures, enabling precise alignment and seamless integration. This approach allows us to build hybrid devices that combine the optical confinement of nanostructures with the unique excitonic and electronic properties of 2D layers. See the example of our hot-carrier generation plasmonic devices here.

Van der Waals Heterostructures

To control the excitonic properties of 2D materials, we assemble them into van der Waals heterostructures, stacking atomically thin layers with designed band alignment and interlayer coupling. By choosing the sequence, spacing, and relative orientation of these layers, we can engineer their excitonic behavior and introduce new interlayer coupling effects. We further incorporate graphene-based electrodes allowing vertical current injection into the semiconductor layers and giving direct access to charge carriers. We also integrate nanophotonic elements into these stacks, enabling enhanced light–matter interactions and new optoelectronic functionalities. This vertical device geometry provides controlled access to excitons and charge carriers, enabling us to probe and manipulate their dynamics. See the example of our LED devices here.

Optoelectronic Measurements

To study the optoelectronic response of our devices, we build and continuously refine high-sensitivity confocal microscope setups tailored for both light-emission and photocurrent measurements. Electrical probes provide direct contact to the selected device, enabling simultaneous optical excitation and electrical readout. Using a tunable laser, we can probe photonic and excitonic resonances, drive interlayer transitions, and record wavelength-dependent photocurrent. By tuning the excitation conditions, we can selectively access excitonic states and investigate their coupling to engineered photonic modes. This integrated approach allows us to map emission, absorption and carrier dynamics across complex heterostructures and nanophotonic architectures. This capability is essential for evaluating device performance and guiding the next designs. See the example of our graphene photodectors here.

Ultrafast Pump-Probe Spectroscopy

We use ultrafast pump–probe spectroscopy to reveal the fundamental physical processes that govern the optical and optoelectronic response of our nanophotonic and 2D-material systems. By exciting the material with a femtosecond pump pulse and probing its response with a time-delayed probe pulse, we resolve carrier dynamics, exciton formation and relaxation pathways, and a range of other processes on the ultrafast timescales. These measurements allow us to uncover mechanisms that cannot be accessed through steady-state techniques and directly link ultrafast physics to device performance. We carry out this work in close collaboration with colleagues who specialize in ultrafast laser systems. See example of our ultrafast graphene-based photodetector here.

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