- The paper presents gate-tunable emissivity in graphene plasmonic resonators, achieving modulation of emission peaks near 750 and 1400 cm⁻¹.
- The study employs chemical vapor deposition graphene on a SiN substrate with a gold back reflector and electron beam lithography to precisely engineer plasmonic behavior.
- The findings reveal that the interplay between plasmon-phonon and plasmon-electron interactions leads to enhanced narrowband mid-IR emission, offering new opportunities in IR source design.
Overview of Electronic Modulation of Infrared Emissivity in Graphene Plasmonic Resonators
This paper presents a sophisticated investigation into the electronic modulation of infrared emissivity employing graphene plasmonic resonators. The paper elucidates the dynamic control of blackbody radiation from graphene-based resonators, illustrating their potential in enhancing radiative emission through plasmonic mechanisms.
Researchers demonstrate that graphene plasmonic resonators can generate antenna-coupled blackbody radiation characterized by narrow spectral emission peaks in the mid-infrared (IR) spectrum. The modulation of these spectral features is achieved by varying the carrier density of the nanoresonators through an electrostatic gate, allowing for dynamic tuning of frequency and intensity.
Methodology and Results
The experimental setup utilizes graphene grown via chemical vapor deposition transferred to a silicon nitride (SiN) substrate. The inclusion of a gold back reflector facilitates electrostatic tuning. The resonators, patterned using electron beam lithography, are designed to enhance thermal radiative emission via plasmon-enhanced mechanisms, significantly when matched to the silicon nitride's vibrational resonance modes.
Significant findings include:
- Gate-Tunable Emissivity: By changing the carrier density, emission frequencies and intensities are modulated, with peaks around 750 cm⁻¹ and 1400 cm⁻¹. The paper particularly highlights a pronounced spectral shift and intensity increase correlated with rising carrier densities and reduced nanoresonator widths.
- Plasmonic Resonances: The higher frequency peak at 1400 cm⁻¹ is attributed to Fabry-Perot-type plasmonic resonances. This peak exhibits strong polarization dependence and shifts with changes in nanostructure width and doping level, consistent with plasmonic behavior in graphene.
- Mixed Emission Mechanisms: The interplay between plasmon-phonon and plasmon-electron interactions underpins the emission from these structures, with thermal radiation enhancement derived from both confined plasmonic modes and substrate phonon emissions.
Implications and Future Directions
The findings are pivotal in advancing applications where controllable thermal emission is crucial, such as in infrared sources for sensing and communication. The high Purcell factors associated with these plasmonic antennas offer a path to develop faster, more precise IR sources than conventional LEDs and classical blackbody emitters.
Practically, by refining the materials and structures involved, greater power outputs could be realized, with SiO₂ substrates suggested as a promising avenue to withstand higher operating temperatures than current SiN substrates. Future research could explore optimizing the material combinations and geometric configurations to broaden the operational bandwidth and efficiency of such tunable emissive devices.
The paper contributes to both theoretical aspects, by elucidating complex emission mechanisms, and practical applications, particularly in the development of tunable narrowband emission sources within the mid-IR range.