Characterizing microscale energy transport in materials with transient grating spectroscopy

Choudhry, Usama; Kim, Tae-Yong; Adams, Melanie; Ranasinghe, Jeewan C.; Yang, Runqing; Liao, Bolin

doi:10.1063/5.0068915

Cited by 16 publications

(2 citation statements)

References 119 publications

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“…Visualization of nanoscale energy transport is a challenging task, requiring high resolution in both space and time, as exciton recombination lifetimes are usually in the picosecond to nanosecond range and transport lengths are on the order of tens of nanometers. To achieve this, ultrafast lasers and high-resolution microscopy have been combined in a variety of techniques that exploit transient absorption (TA) − or photoluminescence (PL) to report on exciton transport.…”

Section: Introductionmentioning

confidence: 99%

Structured Excitation Energy Transfer: Tracking Exciton Diffusion below Sunlight Intensity

Brinatti Vazquez,

Lo Gerfo Morganti,

Vasilev

et al. 2024

ACS Photonics

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With the increasing demand for new materials for light-harvesting applications, spatiotemporal microscopy techniques are receiving increasing attention as they allow direct observation of the nanoscale diffusion of excitons. However, the use of pulsed and tightly focused laser beams generates light intensities far above those expected under sunlight illumination, leading to photodamage and nonlinear effects that seriously limit the accuracy and applicability of these techniques, especially in biological or atomically thin materials. In this work, we present a novel spatiotemporal microscopy technique that exploits structured excitation in order to dramatically decrease the excitation intensity, up to 10,000-fold when compared with previously reported spatiotemporal photoluminescence microscopy experiments. We tested our method in two different systems, reporting the first exciton diffusion measurement at illumination conditions below sunlight, both considering average power and peak exciton densities in an organic photovoltaic sample (Y6), where we tracked the excitons for up to five recombination lifetimes. Next, nanometer-scale energy transport was directly observed for the first time in both space and time in a printed monolayer of the light-harvesting complex 2 from purple bacteria.

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Section: Introductionmentioning

confidence: 99%

Structured Excitation Energy Transfer: Tracking Exciton Diffusion below Sunlight Intensity

Brinatti Vazquez,

Lo Gerfo Morganti,

Vasilev

et al. 2024

ACS Photonics

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“…In its essence, grating involves materials with periodic variations in refractive index, which can be achieved not only through alternating materials but also through the periodic distribution of physical fields within the same material, such as temperature, stress, carrier concentration, etc. This technique is generally called Transient Grating Spectroscopy (TGS) [7][8][9]. TGS employs two coherent pulsed pump beams to generate an interference pattern on the sample surface, as shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Feasibility of a localized mode analysis method in an SOI platform based on carrier grating

Shi,

Li,

Wang

et al. 2024

Appl. Opt.

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In order to measure the intensity of modes that are transmitted inside the devices on the silicon-on-insulator (SOI) platform, researchers usually use pre-processed couplers to make the optical modes diffract out of the chip. However, the output couplers have an influence (e.g., attenuation and wavelength selectivity) on the modes of concern. Besides, as the quantity and variety of devices integrated into the SOI platform continue to escalate, the traditional method also shows limits on detecting devices far from the chip edge. So, is it feasible to directly and locally measure one specific mode’s intensity on some waveguide-based devices like the directional coupler, polarization beam splitter, and so on? Interference of two coherent pump beams has the capability to induce a periodic carrier distribution in the material, thus modulating the refractive index, effectively creating a temporary and erasable diffraction grating. In this study, an off-chip, non-destructive, and localized detection method based on carrier grating is proposed. A theoretical model is developed to calculate carrier dynamics under various pump configurations. Leveraging the finite-difference time-domain (FDTD) method and accounting for free carrier index (FCI) and free carrier absorption (FCA) effects, analysis of the quantitative impact of pump intensity and radius on the diffraction efficiency of the carrier grating in the silicon-on-insulator (SOI) platform and its far-field divergence characteristics is provided. Ultimately, this research contributes to a discussion on several commonly used application scenarios and the feasibility of experimental approaches. A spatial resolution of less than 10 µm and a diffraction efficiency of −15dB while simultaneously maintaining a far-field divergence of 7.8° for the SOI platform are proposed at the end of this article.

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The effective thermal conductivity of micro/nanofilm under different heating conditions using nongray Boltzmann transport equation

Jia,

Sheng,

et al. 2025

International Journal of Thermal Sciences

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Characterizing microscale energy transport in materials with transient grating spectroscopy

Cited by 16 publications

References 119 publications

Structured Excitation Energy Transfer: Tracking Exciton Diffusion below Sunlight Intensity

Structured Excitation Energy Transfer: Tracking Exciton Diffusion below Sunlight Intensity

Feasibility of a localized mode analysis method in an SOI platform based on carrier grating

The effective thermal conductivity of micro/nanofilm under different heating conditions using nongray Boltzmann transport equation

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