Electronic and Thermal Response of Low-Electron-Density Drude Materials to Ultrafast Optical Illumination

Sarkar, Subhajit; Un, Ieng-Wai; Sivan, Yonatan

doi:10.1103/physrevapplied.19.014005

Cited by 9 publications

(31 citation statements)

References 65 publications

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“…At a few tens to hundreds of picoseconds, the metal undergoes thermally induced acoustic oscillations, − and finally, the system reaches thermal equilibrium via heat transfer to the environment. Similar heat dynamics occur in low electron density Drude metals, as well as graphene and other 2D (semi)metals, albeit with shorter time scales: thermalization within the electron system occurs within tens of femtoseconds, followed by electron–phonon-induced cooling on a picosecond time scale …”

Section: Introductionmentioning

confidence: 76%

“…η c , v ( T e ( t ), T l ( t ), t ) = (η c ( T e ( t ), T l ( t ), t ) + η v )/2 is the average level broadening (namely, damping or collision rate) with the indices c and v signifying the final and the initial states in the absorption event. Specifically, η c = η c ,e–e + η c ,e–ph is the damping rate following Matthiessen’s rule, where η c ,e–e and η c ,e–ph are, respectively, the collision rates associated with the electron–electron and electron–phonon interactions. , These temperature- and time-dependent rates are calculated by taking the functional derivative of the corresponding interaction terms with respect to the electron distribution. , η v = 0.1 fs –1 is the collision rate associated with the electrons in the d-band; it is assumed to be time-independent since the electron distribution in the d-band remains nearly unchanged over time. This is due to the high density of states of the d-band.…”

Section: Methodsmentioning

confidence: 99%

“…60,67 These temperature-and time-dependent rates are calculated by taking the functional derivative of the corresponding interaction terms with respect to the electron distribution. 25,61 η v = 0.1 fs −168 is the collision rate associated with the electrons in the d-band; it is assumed to be time-independent since the electron distribution in the dband remains nearly unchanged over time. This is due to the high density of states of the d-band.…”

Section: ■ Conclusionmentioning

confidence: 99%

“…25,61 η v = 0.1 fs −168 is the collision rate associated with the electrons in the d-band; it is assumed to be time-independent since the electron distribution in the dband remains nearly unchanged over time. This is due to the high density of states of the d-band.…”

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confidence: 99%

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Observation of Negative Effective Thermal Diffusion in Gold Films

Block

et al. 2023

ACS Photonics

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Ultrafast light-induced spatiotemporal dynamics in metals in the form of electron and/or phonon heating is a fundamental physical process that has tremendous practical relevance. In particular, understanding the resulting lateral heat transport is of key importance for various (opto)electronic applications and thermal management but has attracted little attention. Here, by using scanning ultrafast thermo-modulation microscopy to track the spatiotemporal electron diffusion in thin gold films, we show that a few picoseconds after the optical pump there is unexpected heat flow from phonons to electrons, accompanied by negative effective thermal diffusion, characterized by shrinking of the spatial region with increased temperature. Peculiarly, this occurs on the intermediate time scale, between the few picosecond long thermalization stage and the many picosecond stage dominated by thermoacoustic vibrations. We accurately reproduced these experimental results by calculating the spatiotemporal photothermal response based on the two-temperature model and an improvement of the standard permittivity model for gold. Our findings facilitate the design of nanoscale thermal management strategies in photonic, optoelectronic, and high-frequency electronic devices.

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Section: Introductionmentioning

confidence: 76%

Section: Methodsmentioning

confidence: 99%

Section: ■ Conclusionmentioning

confidence: 99%

mentioning

confidence: 99%

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Observation of Negative Effective Thermal Diffusion in Gold Films

Block

et al. 2023

ACS Photonics

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“…These studies are currently unveiling the key role of momentum conservation in the electron−phonon interaction in such low-electron-density Drude materials, which leads them to support 8-fold electron temperatures compared to standard plasmonic materials under analogous illumination conditions (Figure 5i). 190,191 Advances in the quest to achieve single-cycle modulation time scales at near-optical frequencies are further stimulating new theoretical developments toward the efficient modeling of time-varying media. Time-varying effects in subwavelength nanostructures introduce unique challenges, 193 as the spatial and temporal scales involved can span several orders of magnitude, and their resolution needs to be comparable in finite-differencing schemes to ensure numerical stability.…”

Section: ■ Enz Media For Time-varying Photonicsmentioning

confidence: 99%

New Horizons in Near-Zero Refractive Index Photonics and Hyperbolic Metamaterials

Lobet,

Kinsey,

Liberal

et al. 2023

ACS Photonics

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The engineering of the spatial and temporal properties of both the electric permittivity and the refractive index of materials is at the core of photonics. When vanishing to zero, those two variables provide efficient knobs to control light–matter interactions. This Perspective aims at providing an overview of the state of the art and the challenges in emerging research areas where the use of near-zero refractive index and hyperbolic metamaterials is pivotal, in particular, light and thermal emission, nonlinear optics, sensing applications, and time-varying photonics.

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Integrated Bolometric Photodetectors Based on Transparent Conductive Oxides from Near‐ to Mid‐Infrared Wavelengths

Gosciniak

2023

Advanced Photonics Research

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On‐chip photodetectors are essential components in optical communications as they convert light into an electrical signal. Photobolometers are a type of photodetector that functions through a resistance change caused by electronic temperature fluctuations upon light absorption. They are widely used in the broad wavelength range from ultraviolet to mid‐infrared (MIR). In this work, a novel waveguide‐integrated bolometer that operates in a wide wavelength range from near‐infrared to MIR is introduced on the standard material platform with the transparent conductive oxides (TCOs) as the active material. This material platform enables the construction of both modulators and photodetectors using the same material, which is fully complementary metal–oxide–semiconductor compatible and easily integrated with passive on‐chip components. The photobolometers proposed here consist of a thin TCO layer placed inside the rib photonic waveguide to enhance light absorption and then heat the electrons in the TCO. This rise in electron temperature leads to decreasing electron mobility and consequential electrical resistance change. In consequence, a responsivity exceeding 10 A W−1can be attained with a mere few microwatts of optical input power. Calculations suggest that further improvements can be expected with lower doping of the TCO, thus opening new doors in on‐chip photodetectors.

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Electronic and Thermal Response of Low-Electron-Density Drude Materials to Ultrafast Optical Illumination

Cited by 9 publications

References 65 publications

Observation of Negative Effective Thermal Diffusion in Gold Films

Observation of Negative Effective Thermal Diffusion in Gold Films

New Horizons in Near-Zero Refractive Index Photonics and Hyperbolic Metamaterials

Integrated Bolometric Photodetectors Based on Transparent Conductive Oxides from Near‐ to Mid‐Infrared Wavelengths

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