Brongersma Group Plasmonics and Photonics at Stanford University

@article{rufangura2025near,

title = {Near unity narrowband infrared thermal emitters on silicon with silicon carbide-germanium metasurfaces},

author = {Patrick Rufangura and Yiyang Cui and Huan Liu and Johan D Carlstrom and Kenneth Crozier and Mark L Brongersma and Yang Yang and Francesca Iacopi},

doi = {10.1063/5.0271574},

year  = {2025},

date = {2025-08-01},

journal = {APL Photonics},

volume = {10},

issue = {8},

abstract = {Traditional thermal emitters are characterized by an incoherent broadband emission spectrum. However, narrowband coherent thermal emission with a high-quality factor in thermally stable materials is highly desirable for applications such as sensing, thermal energy management, thermophotovoltaic systems, and other infrared technologies. Recent advances in engineered nanostructured polaritonic materials, particularly polar dielectric materials in the mid-infrared (MIR) regime, have enabled new approaches to tailoring narrowband coherent thermal emission. The use of low-loss phonon polaritons in thermally stable silicon carbide provides a promising route to MIR thermal emission. In this work, we demonstrate narrowband, near-unity MIR thermal emission by coupling coherent surface phonon polaritons in a SiC layer with a subwavelength germanium grating on a silicon substrate. The demonstrated polarization-dependent thermal emitter, compatible with silicon fabrication technologies for seamless on-chip photonic integration, exhibits narrowband high emissivity (\>90%) at a wavelength of ∼11 μm. Furthermore, we show that these emitters achieve experimental quality factors well above 100 while maintaining significant emission across a wide range of incident angles for MIR radiation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{selvin2025acoustic,

title = {Acoustic wave modulation of gap plasmon cavities},

author = {Skyler P Selvin and Majid Esfandyarpour and Anqi Ji and Yan Joe Lee and Colin Yule and Jung-Hwan Song and Mohammad Taghinejad and Mark L Brongersma},

url = {https://brongersma.stanford.edu/wp-content/uploads/2025/08/science.adv1728-2.pdf

https://www.science.org/stoken/author-tokens/ST-2800/full},

doi = {10.1126/science.adv1728},

year  = {2025},

date = {2025-07-31},

urldate = {2025-07-31},

journal = {Science},

volume = {389},

issue = {6759},

pages = {516-520},

abstract = {The important role of metallic nanostructures in nanophotonics will expand if ways to electrically manipulate their optical resonances at high speed can be identified. We capitalized on electrically driven surface acoustic waves and the extreme light concentration afforded by gap plasmons to achieve this goal. We placed gold nanoparticles in a particle-on-mirror configuration with a few-nanometer-thick, compressible polymer spacer. Surface acoustic waves were then used to tune light scattering at speeds approaching the gigahertz regime. We observed evidence that the surface acoustic waves produced mechanical deformations in the polymer and that ensuing nonlinear mechanical dynamics led to unexpectedly large levels of strain and spectral tuning. Our approach provides a design strategy for electrically driven dynamic metasurfaces and fundamental explorations of high-frequency, polymer dynamics in ultraconfined geometries.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{taghinejad2025ion,

title = {Ion-assisted nanoscale material engineering in atomic layers},

author = {Hossein Taghinejad and Mohammad Taghinejad and Sajjad Abdollahramezani and Qitong Li and Eric V Woods and Mengkun Tian and Ali A Eftekhar and Yuanqi Lyu and Xiang Zhang and Pulickel M Ajayan and Wenshan Cai and Mark L Brongersma and James G Analytis and Ali Adibi},

doi = {10.1021/acs.nanolett.5c02040},

year  = {2025},

date = {2025-06-13},

urldate = {2025-06-13},

journal = {Nano Letters},

volume = {25},

issue = {25},

pages = {10123-10130},

abstract = {Achieving deterministic control over the properties of low-dimensional materials with nanoscale precision is a long-sought goal. Mastering this capability has a transformative effect on the design of multifunctional electrical and optical devices. Here, we present an ion-assisted synthetic technique that enables precise control over the material composition and energy landscape of two-dimensional (2D) atomic crystals. Our method transforms binary transition-metal dichalcogenides, like MoSe2, into ternary MoS2αSe2(1−α) alloys with systematically adjustable compositions, α. By piecewise assembly of the lateral, compositionally modulated MoS2αSe2(1−α) segments within 2D atomic layers, we present a synthetic pathway toward the realization of multicompositional designer materials. Our technique enables the fabrication of advanced 2D structures with arbitrary boundaries, dimensions as small as 30 nm, and fully customizable energy landscapes. Our optical characterizations further showcase the potential for implementing tailored optoelectronics in these engineered 2D crystals.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{guarneri2025dynamic,

title = {Dynamic Excitonic Beam Switching with Atomically‐Thin Binary Blazed Gratings},

author = {Ludovica Guarneri and Thomas Bauer and Qitong Li and Jung‐Hwan Song and Skyler P Selvin and Ashley P Saunders and Fang Liu and Mark L Brongersma and Jorik van de Groep},

doi = {10.1002/adom.202403257},

year  = {2025},

date = {2025-05-12},

urldate = {2025-05-12},

journal = {Advanced Optical Materials},

volume = {13},

issue = {15},

pages = {2403257},

abstract = {Beam steering metasurfaces are ultra-compact optical coatings that offer on-demand redirection of optical power to specific diffraction orders. To achieve this, spatial gradients are commonly introduced in the phase of light scattered by plasmon or Mie resonant nanoparticles within the metasurface grating's unit cell. However, these phase gradients are oftentimes difficult to tune post-fabrication. Recently, excitons in monolayer 2D semiconductors have emerged as a new metasurface building block, due to their strong and electrically-tunable resonant light-matter interaction. These 2D excitonic metasurfaces offer the tantalizing prospect of beam switching within a single monolayer. Here, it is demonstrated how the 2D analog of binary blazed gratings enables such beam switching by mere nanopatterning of a large monolayer WS2, even though nanoscale ribbons of WS2 do not support geometrical resonances. By introducing a gradient in the nanoribbon width within the metasurface unit cell, an amplitude gradient combined with a small phase gradient in the scattered fields results in asymmetric diffraction efficiencies. Using a scattered-field analysis, it is shown that these gradients can be further engineered via interference effects with the substrate reflection. Finally, the electrical tunability of the exciton resonance is leveraged to achieve selective and dynamic beam switching with an atomically-thin metasurface.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{dagli2025ghz,

title = {GHz‐Speed Wavefront Shaping Metasurface Modulators Enabled by Resonant Electro‐Optic Nanoantennas},

author = {Sahil Dagli and Jiyong Shim and Hamish Carr Delgado and Halleh B Balch and Sajjad Abdollahramezani and Chih‐Yi Chen and Varun Dolia and Elissa Klopfer and Jefferson Dixon and Jack Hu and Babatunde Ogunlade and Jung‐Hwan Song and Mark L Brongersma and David Barton and Jennifer A Dionne},

doi = {10.1002/adma.202506790},

year  = {2025},

date = {2025-03-11},

journal = {Advanced Materials},

volume = {e06790},

abstract = {Electrically tunable metasurfaces that control the amplitude and phase of light through biasing of nanoscale antennas present a route to compact modulator devices. However, most platforms face limitations in bandwidth, optical efficiency, and tuning response. Electro-optically tunable metasurfaces achieving both GHz amplitude modulation and transmissive wavefront shaping in the telecom range are presented. The resonant electro-optic nanoantenna design consists of a silicon nanobar atop thin-film lithium niobate, with gold electrodes. The nanobar is a periodically perturbed optical waveguide that supports high quality factor (Q \> 1000) guided mode resonances excited with free-space light. Voltage biasing the lithium niobate tunes its refractive index, modulating the resonance of the nanobar through evanescent mode overlap. Absolute transmittance modulation of 7.1% with ±5 V applied voltage is demonstrated, and the modulation dependence on the resonance quality factor is shown. Additionally, the modulation bandwidth of these devices exceeds 800 MHz, and the electrode limitations on this bandwidth are studied. Finally, how this resonant antenna platform can enable wavefront shaping metasurfaces is shown. A beamsplitting metasurface device is demonstrated, whose diffraction efficiency can be modulated with a bandwidth of 1.03 GHz. The high-speed modulation and wavefront control capabilities of this platform provide a foundation for compact, high-bandwidth free-space communications and sensing devices.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doshi2025thermal,

title = {Thermal Processing Creates Water‐Stable PEDOT: PSS Films for Bioelectronics},

author = {Siddharth Doshi and Margaux OA Forner and Pingyu Wang and Salim El Hadwe and Amy T Jin and Gerwin Dijk and Kenneth Brinson and Juhwan Lim and Antonio Dominguez‐Alfaro and Carina Yi Jing Lim and Alberto Salleo and Damiano G Barone and Guosong Hong and Mark L Brongersma and Nicholas A Melosh and George G Malliaras and Scott T Keene},

doi = {10.1002/adma.202415827},

year  = {2025},

date = {2025-03-03},

urldate = {2025-03-03},

journal = {Advanced Materials},

volume = {37},

issue = {13},

pages = {2415827},

abstract = {Organic mixed ionic-electronic conductors have emerged as a key material for the development of bioelectronic devices due to their soft mechanical properties, biocompatibility, and high volumetric capacitance. In particular, PEDOT:PSS has become a choice material because it is highly conductive, easily processible, and commercially available. However, PEDOT:PSS is dispersible in water, leading to delamination of films when exposed to biological environments. For this reason, chemical cross\textendashlinking agents such as (3-glycidyloxypropyl)trimethoxysilane (GOPS) are used to stabilize PEDOT:PSS films in water, but at the cost of decreased electrical performance. Here, it is shown that PEDOT:PSS thin films become water-stable by simply baking at high temperatures (\>150 °C) for a short time (≈ 2 min). It is shown that heat-treated PEDOT:PSS films are as stable as their chemically-cross\textendashlinked counterparts, with their performance maintained for \>20 days both in vitro and in vivo. The heat-treated films eliminate electrically insulating cross\textendashlinkers, resulting in a 3× increase in volumetric capacitance. Applying thermal energy using a focused femtosecond laser enables direct patterning of 3D PEDOT:PSS microstructures. The thermal treatment method is compatible with a wide range of substrates and is readily substituted into existing workflows for manufacturing devices, enabling its rapid adoption in the field of bioelectronics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}