Brongersma Group Plasmonics and Photonics at Stanford University

@article{li2024optical,

title = {Optical devices as thin as atoms},

author = {Melissa Li and Qitong Li and Mark L Brongersma and Harry A Atwater},

doi = {10.1126/science.adk7707},

year  = {2024},

date = {2024-12-13},

urldate = {2024-12-13},

journal = {Science},

volume = {386},

issue = {6727},

pages = {1226-1228},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ha2024optoelectronic,

title = {Optoelectronic metadevices},

author = {Son Tung Ha and Qitong Li and Joel KW Yang and Hilmi Volkan Demir and Mark L Brongersma and Arseniy I Kuznetsov},

doi = {10.1126/science.adm7442},

year  = {2024},

date = {2024-11-29},

urldate = {2024-11-29},

journal = {Science},

volume = {386},

issue = {6725},

pages = {7442},

abstract = {Metasurfaces have introduced new opportunities in photonic design by offering unprecedented, nanoscale control over optical wavefronts. These artificially structured layers have largely been used to passively manipulate the flow of light by controlling its phase, amplitude, and polarization. However, they can also dynamically modulate these quantities and manipulate fundamental light absorption and emission processes. These valuable traits can extend their application domain to chipscale optoelectronics and conceptually new optical sources, displays, spatial light modulators, photodetectors, solar cells, and imaging systems. New opportunities and challenges have also emerged in the materials and device integration with existing technologies. This Review aims to consolidate the current research landscape and provide perspectives on metasurface capabilities specific to optoelectronic devices, giving new direction to future research and development efforts in academia and industry.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{hoang2024understanding,

title = {Understanding the Impact of Contact-Induced Strain on the Electrical Performance of Monolayer WS2 Transistors},

author = {Lauren Hoang and Marc Jaikissoon and \c{C}a\u{g}ıl K\"{o}ro\u{g}lu and Zhepeng Zhang and Robert KA Bennett and Jung-Hwan Song and Jerry A Yang and Jung-Soo Ko and Mark L Brongersma and Krishna C Saraswat and Eric Pop and Andrew J Mannix},

doi = {10.1021/acs.nanolett.4c02616},

year  = {2024},

date = {2024-10-04},

journal = {Nano Letters},

abstract = {Two-dimensional (2D) electronics require low contact resistance (RC) to approach their fundamental limits. WS2 is a promising 2D semiconductor that is often paired with Ni contacts, but their operation is not well understood considering the nonideal alignment between the Ni work function and the WS2 conduction band. Here, we investigate the effects of contact size on nanoscale monolayer WS2 transistors and uncover that Ni contacts impart stress, which affects the WS2 device performance. The strain applied to the WS2 depends on contact size, where long (1 μm) contacts (RC ≈ 1.7 kΩ·μm) show a 78% reduction in RC compared to shorter (0.1 μm) contacts (RC ≈ 7.8 kΩ·μm). We also find that thermal annealing can relax the WS2 strain in long-contact devices, increasing RC to 8.5 kΩ·μm. These results reveal that thermo-mechanical phenomena can significantly influence 2D semiconductor\textendashmetal contacts, presenting opportunities to optimize device performance through nanofabrication and thermal budget.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ou2024achieving,

title = {Achieving optical transparency in live animals with absorbing molecules},

author = {Zihao Ou and Yi-Shiou Duh and Nicholas J Rommelfanger and Carl HC Keck and Shan Jiang and Kenneth Brinson Jr and Su Zhao and Elizabeth L Schmidt and Xiang Wu and Fan Yang and Betty Cai and Han Cui and Wei Qi and Shifu Wu and Adarsh Tantry and Richard Roth and Jun Ding and Xiaoke Chen and Julia A Kaltschmidt and Mark L Brongersma and Guosong Hong},

doi = {10.1126/science.adm6869},

year  = {2024},

date = {2024-09-06},

journal = {Science},

volume = {385},

issue = {6713},

pages = {eadm6869},

abstract = {Optical imaging plays a central role in biology and medicine but is hindered by light scattering in live tissue. We report the counterintuitive observation that strongly absorbing molecules can achieve optical transparency in live animals. We explored the physics behind this observation and found that when strongly absorbing molecules dissolve in water, they can modify the refractive index of the aqueous medium through the Kramers-Kronig relations to match that of high-index tissue components such as lipids. We have demonstrated that our straightforward approach can reversibly render a live mouse body transparent to allow visualization of a wide range of deep-seated structures and activities. This work suggests that the search for high-performance optical clearing agents should focus on strongly absorbing molecules.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{tertuliano2024high,

title = {High absorptivity nanotextured powders for additive manufacturing},

author = {Ottman A Tertuliano and Philip J DePond and Andrew C Lee and Jiho Hong and David Doan and Luc Capaldi and Mark Brongersma and X Wendy Gu and Manyalibo J Matthews and Wei Cai and Adrian J Lew},

doi = {10.1126/sciadv.adp0003},

year  = {2024},

date = {2024-09-04},

journal = {Science Advances},

volume = {10},

issue = {36},

pages = {eadp0003},

abstract = {The widespread application of metal additive manufacturing (AM) is limited by the ability to control the complex interactions between the energy source and the feedstock material. Here, we develop a generalizable process to introduce nanoscale grooves to the surface of metal powders which increases the powder absorptivity by up to 70% during laser powder bed fusion. Absorptivity enhancements in copper, copper-silver, and tungsten enable energy-efficient manufacturing, with printing of pure copper at relative densities up to 92% using laser energy densities as low as 83 joules per cubic millimeter. Simulations show that the enhanced powder absorptivity results from plasmon-enabled light concentration in nanoscale grooves combined with multiple scattering events. The approach taken here demonstrates a general method to enhance the absorptivity and printability of reflective and refractory metal powders by changing the surface morphology of the feedstock without altering its composition.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kop2024ten,

title = {Ten principles for responsible quantum innovation},

author = {Mauritz Kop and Mateo Aboy and Eline De Jong and Urs Gasser and Timo Minssen and I Glenn Cohen and Mark Brongersma and Teresa Quintel and Luciano Floridi and Raymond Laflamme},

doi = {10.1088/2058-9565/ad3776},

year  = {2024},

date = {2024-04-22},

journal = {Quantum Science and Technology},

volume = {9},

issue = {3},

pages = {035013},

abstract = {This paper proposes a set of guiding principles for responsible quantum innovation. The principles are organized into three functional categories: safeguarding, engaging, and advancing (SEA), and are linked to central values in responsible research and innovation (RRI). Utilizing a global equity normative framework and literature-based methodology, we connect the quantum-SEA categories to promise and perils specific to quantum technology (QT). The paper operationalizes the responsible QT framework by proposing ten actionable principles to help address the risks, challenges, and opportunities associated with the entire suite of second-generation QTs, which includes the quantum computing, sensing, simulation, and networking domains. Each quantum domain has different technology readiness levels, risks, and affordances, with sensing and simulation arguably being closest to market entrance. Our proposal aims to catalyze a much-needed interdisciplinary effort within the quantum community to establish a foundation of quantum-specific and quantum-tailored principles for responsible quantum innovation. The overarching objective of this interdisciplinary effort is to steer the development and use of QT in a direction not only consistent with a values-based society but also a direction that contributes to addressing some of society's most pressing needs and goals.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{guarneri2024temperature,

title = {Temperature-Dependent Excitonic Light Manipulation with Atomically Thin Optical Elements},

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

doi = {10.1021/acs.nanolett.4c00694},

year  = {2024},

date = {2024-04-05},

journal = {Nano Letters},

abstract = {Monolayer 2D semiconductors, such as WS2, exhibit uniquely strong light\textendashmatter interactions due to exciton resonances that enable atomically thin optical elements. Similar to geometry-dependent plasmon and Mie resonances, these intrinsic material resonances offer coherent and tunable light scattering. Thus far, the impact of the excitons’ temporal dynamics on the performance of such excitonic metasurfaces remains unexplored. Here, we show how the excitonic decay rates dictate the focusing efficiency of an atomically thin lens carved directly out of exfoliated monolayer WS2. By isolating the coherent exciton radiation from the incoherent background in the focus of the lens, we obtain a direct measure of the role of exciton radiation in wavefront shaping. Furthermore, we investigate the influence of exciton\textendashphonon scattering by characterizing the focusing efficiency as a function of temperature, demonstrating an increased optical efficiency at cryogenic temperatures. Our results provide valuable insights into the role of excitonic light scattering in 2D nanophotonic devices.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kuznetsov2024roadmap,

title = {Roadmap for Optical Metasurfaces},

author = {Arseniy I Kuznetsov and Mark L Brongersma and Jin Yao and Mu Ku Chen and Uriel Levy and Din Ping Tsai and Nikolay I Zheludev and Andrei Faraon and Amir Arbabi and Nanfang Yu and Debashis Chanda and Kenneth B Crozier and Alexander V Kildishev and Hao Wang and Joel KW Yang and Jason G Valentine and Patrice Genevet and Jonathan A Fan and Owen D Miller and Arka Majumdar and Johannes E Fr\"{o}ch and David Brady and Felix Heide and Ashok Veeraraghavan and Nader Engheta and Andrea Al\`{u} and Albert Polman and Harry A Atwater and Prachi Thureja and Ramon Paniagua-Dominguez and Son Tung Ha and Angela I Barreda and Jon A Schuller and Isabelle Staude and Gustavo Grinblat and Yuri Kivshar and Samuel Peana and Susanne F Yelin and Alexander Senichev and Vladimir M Shalaev and Soham Saha and Alexandra Boltasseva and Junsuk Rho and Dong Kyo Oh and Joohoon Kim and Junghyun Park and Robert Devlin and Ragip A Pala},

doi = {10.1021/acsphotonics.3c00457},

year  = {2024},

date = {2024-02-27},

journal = {ACS photonics},

volume = {11},

issue = {3},

pages = {816-865},

abstract = {Metasurfaces have recently risen to prominence in optical research, providing unique functionalities that can be used for imaging, beam forming, holography, polarimetry, and many more, while keeping device dimensions small. Despite the fact that a vast range of basic metasurface designs has already been thoroughly studied in the literature, the number of metasurface-related papers is still growing at a rapid pace, as metasurface research is now spreading to adjacent fields, including computational imaging, augmented and virtual reality, automotive, display, biosensing, nonlinear, quantum and topological optics, optical computing, and more. At the same time, the ability of metasurfaces to perform optical functions in much more compact optical systems has triggered strong and constantly growing interest from various industries that greatly benefit from the availability of miniaturized, highly functional, and efficient optical components that can be integrated in optoelectronic systems at low cost. This creates a truly unique opportunity for the field of metasurfaces to make both a scientific and an industrial impact. The goal of this Roadmap is to mark this “golden age” of metasurface research and define future directions to encourage scientists and engineers to drive research and development in the field of metasurfaces toward both scientific excellence and broad industrial adoption.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doshi2024direct,

title = {Direct electron beam patterning of electro-optically active PEDOT: PSS},

author = {Siddharth Doshi and Dominik Ludescher and Julian Karst and Moritz Floess and Johan Carlstr\"{o}m and Bohan Li and Nofar Mintz Hemed and Yi-Shiou Duh and Nicholas A Melosh and Mario Hentschel and Mark Brongersma and Harald Giessen},

doi = {10.1515/nanoph-2023-0640},

year  = {2024},

date = {2024-01-04},

urldate = {2023-09-12},

journal = {Nanophotonics},

number = {0},

abstract = {The optical and electronic tunability of the conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has enabled emerging applications as diverse as bioelectronics, flexible electronics, and micro- and nano-photonics. High-resolution spatial patterning of PEDOT:PSS opens up opportunities for novel active devices in a range of fields. However, typical lithographic processes require tedious indirect patterning and dry etch processes, while solution-processing methods such as ink-jet printing have limited spatial resolution. Here, we report a method for direct write nano-patterning of commercially available PEDOT:PSS through electron-beam induced solubility modulation. The written structures are water stable and maintain the conductivity as well as electrochemical and optical properties of PEDOT:PSS, highlighting the broad utility of our method. We demonstrate the potential of our strategy by preparing prototypical nano-wire structures with feature sizes down to 250 nm, an order of magnitude finer than previously reported direct write methods, opening the possibility of writing chip-scale microelectronic and optical devices. We finally use the high-resolution writing capabilities to fabricate electrically-switchable optical diffraction gratings. We show active switching in this archetypal system with \>95 % contrast at CMOS-compatible voltages of +2 V and −3 V, offering a route towards highly-miniaturized dynamic optoelectronic devices.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{taghinejad2023determining,

title = {Determining hot-carrier transport dynamics from terahertz emission},

author = {Mohammad Taghinejad and Chenyi Xia and Martin Hrton and Kyu-Tae Lee and Andrew S Kim and Qitong Li and Burak Guzelturk and Radek Kalousek and Fenghao Xu and Wenshan Cai and Aaron M Lindenberg and Mark L Brongersma},

doi = {10.1126/science.adj5612},

year  = {2023},

date = {2023-10-20},

urldate = {2023-10-20},

journal = {Science},

volume = {382},

issue = {6668},

pages = {299-305},

abstract = {Understanding the ultrafast excitation and transport dynamics of plasmon-driven hot carriers is critical to the development of optoelectronics, photochemistry, and solar-energy harvesting. However, the ultrashort time and length scales associated with the behavior of these highly out-of-equilibrium carriers have impaired experimental verification of ab initio quantum theories. Here, we present an approach to studying plasmonic hot-carrier dynamics that analyzes the temporal waveform of coherent terahertz bursts radiated by photo-ejected hot carriers from designer nano-antennas with a broken symmetry. For ballistic carriers ejected from gold antennas, we find an ~11-femtosecond timescale composed of the plasmon lifetime and ballistic transport time. Polarization- and phase-sensitive detection of terahertz fields further grant direct access to their ballistic transport trajectory. Our approach opens explorations of ultrafast carrier dynamics in optically excited nanostructures.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{sarkar2023physics,

title = {Physics‐Informed Machine Learning for Inverse Design of Optical Metamaterials},

author = {Sulagna Sarkar and Anqi Ji and Zachary Jermain and Robert Lipton and Mark L Brongersma and Kaushik Dayal and Hae Young Noh},

doi = {10.1002/adpr.202300158},

year  = {2023},

date = {2023-10-11},

urldate = {2023-10-11},

journal = {Advanced Photonics Research},

pages = {2300158},

abstract = {Optical metamaterials manipulate light through various confinement and scattering processes, offering unique advantages like high performance, small form factor and easy integration with semiconductor devices. However, designing metasurfaces with suitable optical responses for complex metamaterial systems remains challenging due to the exponentially growing computation cost and the ill-posed nature of inverse problems. To expedite the computation for the inverse design of metasurfaces, a physics-informed deep learning (DL) framework is used. A tandem DL architecture with physics-based learning is used to select designs that are scientifically consistent, have low error in design prediction, and accurate reconstruction of optical responses. The authors focus on the inverse design of a representative plasmonic device and consider the prediction of design for the optical response of a single wavelength incident or a spectrum of wavelength in the visible light range. The physics-based constraint is derived from solving the electromagnetic wave equations for a simplified homogenized model. The model converges with an accuracy up to 97% for inverse design prediction with the optical response for the visible light spectrum as input, and up to 96% for optical response of single wavelength of light as input, with optical response reconstruction accuracy of 99%.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{born2023off,

title = {Off-axis metasurfaces for folded flat optics},

author = {Brandon Born and Sung-Hoon Lee and Jung-Hwan Song and Jeong Yub Lee and Woong Ko and Mark L Brongersma},

doi = {10.1038/s41467-023-41123-x},

year  = {2023},

date = {2023-09-12},

urldate = {2023-09-12},

journal = {Nature Communications},

volume = {14},

issue = {1},

pages = {5602},

abstract = {The overall size of an optical system is limited by the volume of the components and the internal optical path length. To reach the limits of miniaturization, it is possible to reduce both component volume and path length by combining the concepts of metasurface flat optics and folded optics. In addition to their subwavelength component thickness, metasurfaces enable bending conventional folded geometries off axis beyond the law of reflection. However, designing metasurfaces for highly off-axis illumination with visible light in combination with a high numerical aperture is non-trivial. In this case, traditional designs with gradient metasurfaces exhibit low diffraction efficiencies and require the use of deep-subwavelength, high-index, and high-aspect-ratio semiconductor nanostructures that preclude inexpensive, large-area nanofabrication. Here, we describe a design approach that enables the use of low-index (n ≈ 1.5), low-aspect ratio structures for off-axis metagratings that can redirect and focus visible light (λ = 532 nm) with near-unity efficiency. We show that fabricated optical elements offer a very large angle-of-view (110°) and lend themselves to scalable fabrication by nano-imprint lithography.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{li2023purcell,

title = {A Purcell-enabled monolayer semiconductor free-space optical modulator},

author = {Qitong Li and Jung-Hwan Song and Fenghao Xu and Jorik van de Groep and Jiho Hong and Alwin Daus and Yan Joe Lee and Amalya C Johnson and Eric Pop and Fang Liu and Mark L Brongersma},

doi = {10.1038/s41566-023-01250-9},

year  = {2023},

date = {2023-07-23},

urldate = {2023-07-23},

journal = {Nature Photonics},

volume = {17},

issue = {10},

pages = {897-903},

abstract = {Dephasing and non-radiative decay processes limit the performance of a wide variety of quantum devices at room temperature. Here we illustrate a general pathway to notably reduce the detrimental impact of these undesired effects through photonic design of the device electrodes. Our design facilitates a large Purcell enhancement that speeds up competing, desired radiative decay while also enabling convenient electrical gating and charge injection functions. We demonstrate the concept with a free-space optical modulator based on an atomically thin semiconductor. By engineering the plasmonic response of a nanopatterned silver gate pad, we successfully enhance the radiative decay rate of excitons in a tungsten disulfide monolayer by one order of magnitude to create record-high modulation efficiencies for this class of materials at room temperature. We experimentally observe a 10% reflectance change as well as 3 dB signal modulation, corresponding to a 20-fold enhancement compared with modulation using a suspended monolayer in vacuum. We also illustrate how dynamic control of light fields can be achieved with designer surface patterns. This research highlights the benefits of applying radiative decay engineering as a powerful tool in creating high-performance devices that complements substantial efforts to improve the quality of materials.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{song2023transfer,

title = {Transfer Matrix Method-Compatible Model for Metamaterial Stacks},

author = {Jung-Hwan Song and Philippe Lalanne and Min-Kyo Seo and Mark L Brongersma},

doi = {10.1021/acsphotonics.3c00693},

year  = {2023},

date = {2023-07-18},

urldate = {2023-07-18},

journal = {ACS Photonics},

volume = {10},

issue = {8},

pages = {2948-2954},

abstract = {Mean-field theory-based effective refractive index models are widely used to design optical metamaterials and interpret their optical properties. However, emerging applications where metamaterials are embedded into layered device architectures require a detailed consideration of the metamaterial’s dispersive properties and interfacial boundary conditions, which are beyond the scope of the mean-field theory for homogeneous bulk media. Here, we describe an approach to calculate the optical transfer function for one-dimensional optical metamaterials that includes the dispersive properties of the effective index as well as the effective interfacial impedance. We address the boundary conditions at a metamaterial interface by a complex-valued effective interfacial impedance. Combined with the effective refractive index, the effective interfacial impedance enables a description of the optical transfer for 1D optical metamaterials with the transfer matrix method. This opens up scalable design of one-dimensional multilayered structures that include metamaterial layers. We illustrate the approach with the design of a metamaterial-based antireflection coating for a thin-film photodetector.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{fan2023ultrafast,

title = {Ultrafast Wavefront Shaping via Space-Time Refraction},

author = {Qingyuan Fan and Amr M Shaltout and Jorik van de Groep and Mark L Brongersma and Aaron M Lindenberg},

doi = {10.1021/acsphotonics.3c00498},

year  = {2023},

date = {2023-07-03},

urldate = {2023-07-03},

journal = {ACS Photonics},

volume = {10},

issue = {8},

pages = {2467-2473},

abstract = {A myriad of metasurfaces have been demonstrated that manipulate light by spatially structuring thin optical layers. Manipulation of the optical properties of such layers in both space and time can unlock new physical phenomena and enable new optical devices. Examples include photon acceleration and frequency conversion, which modifies Snell’s relation to a more general, nonreciprocal form. Here, we combine theory and experiment to realize wavefront shaping and frequency conversion on subpicosecond time-scales by inducing space-time refractive index gradients in epsilon-near-zero (ENZ) films with femtosecond light pulses. We experimentally tune wavefront steering by controlling the incident angle of the beams and the pump\textendashprobe delay without the need for nanostructure fabrication. As a demonstration of this approach, we leverage the ultrafast, high-bandwidth optical response of transparent oxides in their ENZ wavelength range to create large refractive index gradients and new types of nonreciprocal, ultrafast two-dimensional (2D) optics, including an ultrathin transient lens.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{liu2023controlling,

title = {Controlling Valley-Specific Light Emission from Monolayer MoS2 with Achiral Dielectric Metasurfaces},

author = {Yin Liu and Sze Cheung Lau and Wen-Hui Cheng and Amalya Johnson and Qitong Li and Emma Simmerman and Ouri Karni and Jack Hu and Fang Liu and Mark L Brongersma and Tony F Heinz and Jennifer A Dionne},

doi = {10.1021/acs.nanolett.3c01630},

year  = {2023},

date = {2023-06-22},

urldate = {2023-06-22},

journal = {Nano Letters},

abstract = {Excitons in two-dimensional transition metal dichalcogenides have a valley degree of freedom that can be optically manipulated for quantum information processing. Here, we integrate MoS2 monolayers with achiral silicon disk array metasurfaces to enhance and control valley-specific absorption and emission. Through the coupling to the metasurface electric and magnetic Mie modes, the intensity and lifetime of the emission of neutral excitons, trions, and defect bound excitons can be enhanced and shortened, respectively, while the spectral shape can be modified. Additionally, the degree of polarization (DOP) of exciton and trion emission from the valley can be symmetrically enhanced at 100 K. The DOP increase is attributed to both the metasurface-enhanced chiral absorption of light and the metasurface-enhanced exciton emission from the Purcell effect. Combining Si-compatible photonic design with large-scale 2D materials integration, our work makes an important step toward on-chip valleytronic applications approaching room-temperature operation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{van2023impact,

title = {Impact of substrates and quantum effects on exciton line shapes of 2D semiconductors at room temperature},

author = {Jorik van de Groep and Qitong Li and Jung-Hwan Song and Pieter G Kik and Mark L Brongersma},

doi = {10.1515/nanoph-2023-0193},

year  = {2023},

date = {2023-06-20},

urldate = {2023-06-20},

journal = {Nanophotonics},

issue = {0},

abstract = {Exciton resonances in monolayer transition-metal dichalcogenides (TMDs) provide exceptionally strong light\textendashmatter interaction at room temperature. Their spectral line shape is critical in the design of a myriad of optoelectronic devices, ranging from solar cells to quantum information processing. However, disorder resulting from static inhomogeneities and dynamical fluctuations can significantly impact the line shape. Many recent works experimentally evaluate the optical properties of TMD monolayers placed on a substrate and the line shape is typically linked directly to the material’s quality. Here, we highlight that the interference of the substrate and TMD reflections can strongly influence the line shape. We further show how basic, room-temperature reflection measurements allow investigation of the quantum mechanical exciton dynamics by systematically controlling the substrate reflection with index-matching oils. By removing the substrate contribution with properly chosen oil, we can extract the excitonic decay rates including the quantum mechanical dephasing rate. The results provide valuable guidance for the engineering of exciton line shapes in layered nanophotonic systems.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{lee2023multi,

title = {Multi‐resonant Mie Resonator Arrays for Broadband Light Trapping in Ultrathin c‐Si Solar Cells},

author = {Nayeun Lee and Muyu Xue and Jiho Hong and Jorik van de Groep and Mark L Brongersma},

doi = {10.1002/adma.202210941},

year  = {2023},

date = {2023-05-02},

urldate = {2023-05-02},

journal = {Advanced Materials},

pages = {2210941},

abstract = {Effective photon management is critical to realize high power conversion efficiencies for thin crystalline Si (c-Si) solar cells. Standard few-100-µm-thick bulk cells achieve light trapping with macroscopic surface textures covered by thin, continuous antireflection coatings. Such sizeable textures are challenging to implement on ultrathin cells. Here, we illustrate how nanoscale Mie-resonator-arrays with a bi-modal size distribution support multiple resonances that can work in concert to achieve simultaneous antireflection and light-trapping across the broad solar spectrum. We experimentally demonstrate the effectiveness of these light-trapping antireflection coatings (LARCs) on a 2.8-µm-thick c-Si solar cell. The measured short-circuit current and corresponding power conversion efficiency are notably improved, achieving efficiencies as high as 11.2%. Measurements of the saturation current density on completed cells indicate that thermal oxides can effectively limit surface recombination. The presented design principles are applicable to a wide range of solar cells.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Zubritskaya2023,

title = {Dynamically Tunable Optical Cavities with Embedded Nematic Liquid Crystalline Networks},

author = {Irina Zubritskaya and Rafael Cichelero and Ihar Faniayeu and Daniele Martella and Sara Nocentini and Per Rudquist and Diederik Sybolt Wiersma and Mark L. Brongersma},

doi = {10.1002/adma.202209152},

year  = {2023},

date = {2023-01-22},

urldate = {2023-01-22},

journal = {Advanced Materials},

pages = {2209152},

abstract = {Abstract Tunable metal\textendashinsulator\textendashmetal (MIM) Fabry\textendashP\'{e}rot (FP) cavities that can dynamically control light enable novel sensing, imaging and display applications. However, the realization of dynamic cavities incorporating stimuli-responsive materials poses a significant engineering challenge. Current approaches rely on refractive index modulation and suffer from low dynamic tunability, high losses, and limited spectral ranges, and require liquid and hazardous materials for operation. To overcome these challenges, a new tuning mechanism employing reversible mechanical adaptations of a polymer network is proposed, and dynamic tuning of optical resonances is demonstrated. Solid-state temperature-responsive optical coatings are developed by preparing a monodomain nematic liquid crystalline network (LCN) and are incorporated between metallic mirrors to form active optical microcavities. LCN microcavities offer large, reversible and highly linear spectral tuning of FP resonances reaching wavelength-shifts up to 40 nm via thermomechanical actuation while featuring outstanding repeatability and precision over more than 100 heating\textendashcooling cycles. This degree of tunability allows for reversible switching between the reflective and the absorbing states of the device over the entire visible and near-infrared spectral regions, reaching large changes in reflectance with modulation efficiency ΔR = 79%.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}