Accessing the electric field of light with petahertz bandwidths in ambient air is a rapidly advancing frontier, essential for probing ultrafast dynamics driven by classical or quantum ultrashort pulses. Near-petahertz fieldoscopy has recently demonstrated sub-cycle access to light-matter interactions, enabling label-free spectro-microscopy of liquids and solids with unprecedented spatiotemporal resolution, detection sensitivity, and dynamic range. However, current implementations still rely on temporal scanning and averaging over many laser pulses. Here, we introduce photonic time-stretch fieldoscopy, enabling single-shot electric-field detection at near-petahertz frequencies. Numerical results demonstrate that integrating fieldoscopy with a nonlinear time lens enables the real-time acquisition of ultrashort optical waveforms with a detection bandwidth approaching petahertz. The resulting large temporal aperture and attosecond resolution allow direct single-shot detection of transient electric fields generated in solid or liquid samples. This concept opens new avenues for petahertz electronics, ultrafast spectro-microscopy, and the study of dynamic, non-repetitive optical phenomena
Ultrafast nonlinear dynamics of indium tin oxide nanocrystals probed via fieldoscopy
Andreas Herbst,
Anchit Srivastava,
Kilian Scheffter,
Soyeon Jun,
Steffen Gommel,
Luca Rebecchi,
Sidharth Kuriyil,
Andrea Rubino,
Nicolo Petrini, et al.
Scalable, high-speed, small-footprint photonic switching platforms are essential for advancing optical communication. An effective optical switch must operate at high duty cycles with fast recovery times, while maintaining substantial modulation depth and full reversibility. Colloidal nanocrystals, such as indium tin oxide (ITO), offer a scalable platform to meet these requirements. In this work, the transmission of ITO nanocrystals near their epsilon-near-zero wavelength is modulated by two-cycle optical pulses at a repetition rate of one megahertz. The modulator exhibits a broad bandwidth spanning from 2 to 2.5 µm. Sensitive fieldoscopy measurements resolve the transient electric-field response of the ITO for the first time, showing that the modulation remains reversible for excitation fluences up to 1.2 mJ cm−2 with a modulation depth of 10%, and becomes fully irreversible beyond 3.3 mJ cm−2, while reaching modulation depth of up to 20%. Field sampling further indicates that at higher excitation fluences, the relative contribution from the first cycle of the optical pulses is reduced. These findings are crucial for the development of all-optical switching, telecommunications, and sensing technologies capable of operating at terahertz switching frequencies.
Bridging the Digital Divide
Hanieh Fattahi,
Asghar Ghorbani
Optics and Photonics News
September 2025
(2025)
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Limited infrastructure, scarce educational resources, and unreliable internet access often hinder physics and photonics education in underdeveloped regions. These barriers create deep inequities in Science, Technology, Engineering, and Mathematics (STEM) education. This article explores how Small Language Models (SLMs)-compact, AI-powered tools that can run offline on low-power devices, offering a scalable solution. By acting as virtual tutors, enabling native-language instruction, and supporting interactive learning, SLMs can help address the shortage of trained educators and laboratory access. By narrowing the digital divide through targeted investment in AI technologies, SLMs present a scalable and inclusive solution to advance STEM education and foster scientific empowerment in marginalized communities.
Recent advances in ultrafast lasers enable high-sensitivity, label-free detection of molecular responses in liquids at near-peta hertz frequencies, improving measurement sensitivity and speed in spectroscopy.
Femtosecond Fieldoscopy for super-resolution label-free microscopy
Soyeon Jun,
Andreas Herbst,
Kilian Scheffter,
Daniel Wehner,
Anchit Srivastava,
Hanieh Fattahi
Accessing complete electric field information of a laser pulse interacting with a medium at visible to near-infrared (near-petahertz) frequencies has traditionally required complex laboratory systems operating in vacuum conditions. Recent advancements, however, have enabled the measurement of electric fields at near-petahertz frequencies in ambient air. This capability is critical for understanding ultrafast phenomena and for achieving quantitative detection of molecular species in various samples. This article introduces Femtosecond Fieldoscopy, a field-resolved detection technique for label-free spectroscopy and microscopy. This approach delivers exceptional detection sensitivity and dynamic range at petahertz bandwidths by combining attosecond temporal resolution with temporal isolation of target molecular responses from environmental and excitation pulse effects. Furthermore, Femtosecond Fieldoscopy holds promise for achieving sub-diffraction spatial resolution, opening new horizons for high-precision label-free spectro-microscopy.
Kontakt
Forschungsgruppe Hanieh Fattahi
Max-Planck-Institut für die Physik des Lichts Staudtstr. 2 91058 Erlangen
