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| Open AccessSub-Doppler optical-optical double-resonance spectroscopy using a cavity-enhanced frequency comb probe
Probing molecules in excited vibrational states requires precise methods to extract the spectroscopic parameters. Here the authors demonstrate optical-optical double-resonance spectroscopy of excited-bands of methane using single pass high power continuous wave pump and cavity-enhanced frequency comb probe.
- Vinicius Silva de Oliveira
- , Isak Silander
- & Aleksandra Foltynowicz
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Article
| Open AccessEngineered NIR-II fluorophores with ultralong-distance molecular packing for high-contrast deep lesion identification
To achieve high-contrast in fluorescence imaging of deep tissues is challenging. Here, the authors develop NIR-II fluorescent small molecules with high brightness and emission extending to 1900 nm, enabling in vivo imaging of deep tissues with enhanced signal-to-background ratios.
- Zhe Feng
- , Yuanyuan Li
- & Jun Qian
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| Open AccessRemote near-field spectroscopy of vibrational strong coupling between organic molecules and phononic nanoresonators
Vibrational strong coupling (VSC) promises ultrasensitive IR spectroscopy and modification of material properties. Here, nanoscale mapping of VSC between organic molecules and individual IR nanoresonators is achieved by remote near-field spectroscopy.
- Irene Dolado
- , Carlos Maciel-Escudero
- & Rainer Hillenbrand
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| Open AccessNanoscale heterogeneity of ultrafast many-body carrier dynamics in triple cation perovskites
The optoelectronic performance of lead halide perovskite in highfluence applications are hindered by heterogeneous multi-polaron interactions in the nanoscale. Here, Nishda et al. spatially resolve sub-ns relaxation dynamics on the nanometer scale by ultrafast infrared pumpprobe nanoimaging.
- Jun Nishida
- , Peter T. S. Chang
- & Markus B. Raschke
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Article
| Open AccessCoherent helicity-dependent spin-phonon oscillations in the ferromagnetic van der Waals crystal CrI3
CrI3 is a van der Waals material which exhibits magnetic ordering down to the monolayer limit. Here, using ultrafast optical spectroscopy, Padmanabhan and Buessen et al. investigate the coupling between the magnetically ordered spins and lattice distortions, finding a coherent spin-coupled phonon mode.
- P. Padmanabhan
- , F. L. Buessen
- & R. P. Prasankumar
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| Open AccessNano-spectroscopy of excitons in atomically thin transition metal dichalcogenides
Excitons play an important role in the optical properties of 2D semiconductors, but their spatial characterization is usually constrained by the diffraction limit. Here, the authors report near-field optical spectroscopy of 2D transition metal dichalcogenides with 20 nm resolution, revealing their spatially dependent excitonic spectra and complex dielectric function.
- Shuai Zhang
- , Baichang Li
- & D. N. Basov
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| Open AccessNano-imaging photoresponse in a moiré unit cell of minimally twisted bilayer graphene
Here, the authors use a nanoscale probe to study the photoresponse within a single moiré unit cell of minimally twisted bilayer graphene, and observe an intricate photo-thermoelectric response attributed to the Seebeck coefficient variation at AB-BA domain boundaries.
- Niels C. H. Hesp
- , Iacopo Torre
- & Frank H. L. Koppens
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| Open AccessShortwave-infrared meso-patterned imaging enables label-free mapping of tissue water and lipid content
Quantifying lipid and water content in tissues non-invasively is difficult, and no method exists to quantify lipids in blood non-invasively. Here the authors develop an imaging approach called shortwave infrared meso-patterned imaging (SWIR-MPI) to detect and spatially map tissue water and lipids in preclinical models.
- Yanyu Zhao
- , Anahita Pilvar
- & Darren Roblyer
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Article
| Open AccessPolariton-driven phonon laser
Efficient generation of phonons is an important ingredient for a prospective electrically-driven phonon laser for coherent control of quantum systems. Here, the authors report on laser-like phonon emission in a hybrid semiconductor microcavity that optomechanically couples BEC polaritons with phonons.
- D. L. Chafatinos
- , A. S. Kuznetsov
- & A. Fainstein
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| Open Accessas-Indaceno[3,2,1,8,7,6-ghijklm]terrylene as a near-infrared absorbing C70-fragment
The synthesis of hydrocarbons with attractive electronic structures remains challenging. Here, the authors describe the synthesis and properties of the C70 fragment as-indaceno[3,2,1,8,7,6-ghijklm]terrylene, which exhibits near-infrared (NIR) absorption.
- Yuki Tanaka
- , Norihito Fukui
- & Hiroshi Shinokubo
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Article
| Open AccessMode-phase-difference photothermal spectroscopy for gas detection with an anti-resonant hollow-core optical fiber
Typically, the performance of the state-of-the-art laser sensors is insufficient for many high precision applications. Here, the authors report mode-phase-difference photothermal spectroscopy with a dual-mode anti-resonant hollow-core optical fiber and demonstrate acetylene detection with ultra-high sensitivity.
- Pengcheng Zhao
- , Yan Zhao
- & Pu Wang
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| Open AccessTime-of-flight resolved light field fluctuations reveal deep human tissue physiology
Diffuse optical flowmetry is widely used to assess blood flow dynamics, but has remained difficult to interpret. Here, the authors use interferometric near-infrared spectroscopy, revealing additional information about optical phase and time-of-flight, and observe the Brownian nature of blood flow dynamics in humans.
- Oybek Kholiqov
- , Wenjun Zhou
- & Vivek J. Srinivasan
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| Open AccessSingle-defect spectroscopy in the shortwave infrared
Chemical defects endow materials with unique properties but their investigation is challenging due to their small footprint. Here the authors develop a high throughput shortwave infrared spectroscopy method enabling spectral identification and quantitative counting of fluorescent chemical defects at the single defect level.
- Xiaojian Wu
- , Mijin Kim
- & YuHuang Wang
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| Open AccessThe valley Zeeman effect in inter- and intra-valley trions in monolayer WSe2
The unique valley and spin texture of atomically thin transition metal dichalcogenides (TMDs) allows the observation of the valley Zeeman effect for neutral and charged excitons. Here, the authors unveil the underlying physics of the magneto-optical response and valley Zeeman splitting of trions in tungsten-based TMDs.
- T. P. Lyons
- , S. Dufferwiel
- & A. I. Tartakovskii
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| Open AccessA phase-stable dual-comb interferometer
Dual-comb interferometry promises to be a high-precision metrology technique, but is hindered by short coherence times that limit the maximum number of averages. Here, Chen et al. achieve mutual coherence times of almost 2000 s by feed-forward stabilization of the carrier-envelope offsets.
- Zaijun Chen
- , Ming Yan
- & Nathalie Picqué
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| Open AccessGeneralized Fano lineshapes reveal exceptional points in photonic molecules
Fano lineshapes are found in many photonic systems where discrete and extended spectra interfere. Here, the authors extend this description and introduce generalized Fano lineshapes to describe the results from hyperspectral mapping around an exceptional point in a coupled-cavity system.
- Niccolò Caselli
- , Francesca Intonti
- & Massimo Gurioli
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| Open AccessDual-comb spectroscopic ellipsometry
Spectroscopic ellipsometry is an established technique to characterize the optical properties of a material. Here, Minamikawa et al. combine the method with dual-comb spectroscopy, which allows them to obtain ellipsometric parameters including the phase difference between s-polarized and p-polarized light.
- Takeo Minamikawa
- , Yi-Da Hsieh
- & Takeshi Yasui
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| Open AccessNeutral and charged inter-valley biexcitons in monolayer MoSe2
Atomically thin transition metal dichalcogenides host excitons and trions, however higher-order states, although possible, are difficult to identify experimentally. Here, the authors perform polarization-resolved coherent spectroscopy to unveil the signature of neutral and charged inter-valley biexcitons in monolayer MoSe2.
- Kai Hao
- , Judith F. Specht
- & Galan Moody
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| Open AccessNon-invasive imaging and cellular tracking of pulmonary emboli by near-infrared fluorescence and positron-emission tomography
Functional imaging of proteolytic activity is an emerging strategy to guide patient diagnosis and monitor clinical outcome. Here the authors present a peptide-based probe to detect and localize thrombin activity ex vivoand non-invasively in mouse models of wounding and pulmonary thrombosis.
- Michael J. Page
- , André L. Lourenço
- & Charles S. Craik