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Manipulating broadband fields in scattering media is a modern challenge across photonics and other wave domains. Recent studies have shown that complex propagation in scattering media can be harnessed to manipulate broadband light wave packets in space-time for focusing, imaging, and computing applications. Interestingly, while many proposed methodologies operate on intensity-based assessment of scattered fields, often in the spectral domain, from a pure transmission-function perspective, scattering operates as a linear field-level combinatory process, i.e., the superposition of transformation of unit excitations. As a result, we recently demonstrated that gaining experimental access to instantaneous scattered fields, as available through time-domain spectroscopy in the terahertz (THz) spectral range, in conjunction with sparse light excitation typical of ghost imaging, provides a key advantage in enabling the functionalisation of scattering, exposing a novel modelling paradigm. In this paper, we provide experimental proof of reconstructing 1-dimensional object features through a scattering medium using a fully broadband THz time-domain approach.

Intracoronary imaging (ICI) facilitates stent implant by characterizing the lesion calcification, providing accurate vessel dimensions, and optimizing the stent results. We sought to investigate the outcomes of routine ICI versus coronary angiography (CA) to guide percutaneous coronary intervention (PCI) with second- and third-generation drug-eluting stents. A systematic search of PubMed, Medline, and Cochrane databases was conducted from their inception to July 16, 2022 for randomized controlled trials comparing routine ICI with CA. The primary outcome was major adverse cardiovascular events. The secondary outcomes of interest were target lesion revascularization, target vessel revascularization, myocardial infarction, stent thrombosis, and cardiac and all-cause mortality. A random-effects model was used to calculate the pooled incidence and relative risk (RR) with 95% confidence intervals (CIs). A total of 9 randomized controlled trials with 5,879 patients (2,870 ICI-guided and 3,009 CA-guided PCI) met the inclusion criteria. The ICI and CA groups were similar in demographic characteristics and co-morbidity profiles. Compared with CA, patients in the routine ICI-guided PCI group had lower rates of major adverse cardiovascular events (RR 0.61, 95% CI 0.48 to 0.78, p <0.0001), target lesion revascularization (RR 0.60, 95% CI 0.43 to 0.83, p = 0.002), target vessel revascularization (RR 0.72, 95% CI 0.51 to 1.00, p = 0.05), and myocardial infarction (RR 0.48, 95% CI 0.25 to 0.95, p = 0.03). There were no significant differences in stent thrombosis or cardiac/all-cause mortality between the 2 strategies. In conclusion, routine ICI-guided PCI strategy, compared with CA guidance alone, is associated with improved clinical outcomes, largely driven by lower repeat revascularization.

Spintronic emitters promise to revolutionise terahertz (THz) sources by converting ultrafast optical pulses into broadband THz radiation without phase-matching constraints. Because the conversion relies on spin-current injection across a nanometre-thin magnetic layer, its efficiency is ordinarily limited by weak optical coupling. Here, we present a demonstration of a drop-casting based approach to introduce ultrafast plasmonic-mediated coupling: a sparse-layer of silica–gold core–shell nanoparticles is deposited directly onto a W/Fe/Pt spintronic trilayer. This sparse (≈ 6%) decoration leads to a measured enhancement of the emitted THz peak field between 1.1x and 1.6x relative to the bare stack as the angle is increased from 0° to 75°, pointing to a very high local conversion enhancement for this low-coverage spintronic emitter compared with the bare stack, with the maximum emission reached at 0°. This demonstration points to a viable pathway toward highly efficient spintronic terahertz emitters with potential applications in spectroscopy, imaging, and ultrafast technologies.

Terahertz (THz) imaging is a rapidly emerging field, thanks to many potential applications in diagnostics, manufacturing, medicine and material characterisation. However, the relatively coarse resolution stemming from the large wavelength limits the deployment of THz imaging in micro- and nano-technologies, keeping its potential benefits out-of-reach in many practical scenarios and devices. In this context, single-pixel techniques are a promising alternative to imaging arrays, in particular when targeting subwavelength resolutions. In this work, we discuss the key advantages and practical challenges in the implementation of time-resolved nonlinear ghost imaging (TIMING), an imaging technique combining nonlinear THz generation with time-resolved time-domain spectroscopy detection. We numerically demonstrate the high-resolution reconstruction of semi-transparent samples, and we show how the Walsh–Hadamard reconstruction scheme can be optimised to significantly reduce the reconstruction time. We also discuss how, in sharp contrast with traditional intensity-based ghost imaging, the field detection at the heart of TIMING enables high-fidelity image reconstruction via low numerical-aperture detection. Even more striking—and to the best of our knowledge, an issue never tackled before—the general concept of “resolution” of the imaging system as the “smallest feature discernible” appears to be not well suited to describing the fidelity limits of nonlinear ghost-imaging systems. Our results suggest that the drop in reconstruction accuracy stemming from non-ideal detection conditions is complex and not driven by the attenuation of high-frequency spatial components (i.e., blurring) as in standard imaging. On the technological side, we further show how achieving efficient optical-to-terahertz conversion in extremely short propagation lengths is crucial regarding imaging performance, and we propose low-bandgap semiconductors as a practical framework to obtain THz emission from quasi-2D structures, i.e., structure in which the interaction occurs on a deeply subwavelength scale. Our results establish a comprehensive theoretical and experimental framework for the development of a new generation of terahertz hyperspectral imaging devices.

Laser cavity-solitons can appear in a microresonator-filtered laser when judiciously balancing the slow nonlinearities of the system. Under certain conditions, such optical states can be made to self-emerge and recover spontaneously, and the understanding of their robustness is critical for practical applications. Here, we study the formation of a bonded state comprising a soliton and a blue-detuned continuous wave, whose coexistence is mediated by dispersion in the nonlinear refractive index. Our real-time dispersive Fourier transform measurements, supported by comprehensive theoretical analysis, reveal the presence of an elastic bonding between the two states, resulting in an enhancement of the soliton’s robustness. Cavity-solitons in microresonator-filtered fibre lasers are robust states with self-recovery capabilities that emerge when a delicate balance of energy-dependent nonlinearities is achieved. In this work, the authors make use of the dispersive Fourier transform to understand the dynamics leading to a soliton bonded with a quasi-continuous wave.

Photonic Ising machines leverage large-scale parallelism for solving large combinatorial problems, yet multiple minima hamper Metropolis-based algorithm. A double single-pixel detection approach enables adiabatic energetic transitions from nonlocal to local Hamiltonians, finding the ground state of complex landscapes.

Terahertz Nonlinear Ghost Imaging introduces a groundbreaking method for object sampling at spatial-temporal levels, achieving super-resolution (i.e., beyond the diffraction limit). Our theoretical and experimental endeavour seeks to leverage this technique, enabling arbitrary field-level waveform manipulation through intricate propagation in scattering environments. This approach facilitates essential agile waveform adjustment, made possible through near-field interactions between terahertz sources and scattering media.

In the framework of optical frequency conversion, metasurfaces have elevated the potential for effective interfacial nonlinear coefficients through various modes of field localization. For the generation of pulsed ultrafast terahertz (THz) signals, metasurfaces present a viable alternative in the domain of surface-scalable sources driven by low-power oscillators (using nJ pulses). However, recent innovations have predominantly relied on surface plasmons (metals) and, more broadly, on excitations within non-transparency windows—conditions that typically impose limitations on applications and the choice of platforms. Here, we demonstrate the utilization of a fully-dielectric, fully transparent semiconductor that exploits surface-nano-structure-mediated resonances alongside its inherent quadratic nonlinear response. Our system exhibits a remarkable 40-fold efficiency enhancement in comparison to the non-decorated substrate.

Rare earth elements (REEs) consist of 17 naturally occurring elements and are split into light and heavy REEs. REEs have significant uses in high-technology and clean energy applications. The rare earth element market has been significantly affected by supply risk in the past, owing o China’s monopoly across the entire value chain. Since the last REE crisis between 2009 and 2013, the rest of the world has made little progress to bring new REE projects online. Reasons for this include environmental, financial and metallurgical constraints that face most REE projects. Currently, global REE production is approximately 170,000 tonnes. China is responsible for more than 80% of this production and is essentially the sole producer of heavy REEs such as dysprosium and terbium. Australia and the USA are the next largest producers of REEs, primarily due to the Mt Weld and Mountain Pass mining operations respectively. Although it is unclear how large the Chinese resource inventory is, due to its non-transparent reporting, it is certain that its REE endowment largely overshadows that of the rest of the world. Due to China’s supply dominance, there is still a supply risk, resulting from geological and jurisdictional scarcity, that affects the rest of the world.Drivers of REE demand include population and economic growth as well as a global desire to reduce carbon emissions in order to combat climate change, in accordance with the Paris Agreement. The expected increased future demand for certain REEs, notably neodymium (Nd), praseodymium, dysprosium (Dy) and terbium, raises concerns around supply of these metals. These elements are primarily used in clean technology applications such as permanent magnets. Permanent magnet technology is expected to grow at much higher rates than other REE applications, due to their uses in electric vehicles and wind turbines. By 2025, a total of 28,385 and 7,880 tonnes of Nd and Dy respectively will be required to satisfy the permanent magnet demand for wind turbines, electric vehicles and electric bikes alone. With forecasted production rates, this will likely result in a Nd deficit of more than 1,000 tonnes and a Dy deficit of more than 5,000 tonnes by 2025.