Nature Photonics最新文献

Correction to: Nature Photonics https://doi.org/10.1038/s41566-022-01058-z, published online 25 August 2022.

Brillouin microscopy is an emerging optical elastography technique that can be used to assess mechanical properties of biological samples in a three-dimensional, all-optical and hence non-contact fashion. However, the low cross-section of spontaneous Brillouin scattering produces weak signals that often necessitate prolonged exposure times or illumination dosages that are potentially harmful for biological samples. Here we present a new approach for highly multiplexed and therefore rapid spectral acquisition of the Brillouin-scattered light. Specifically, by exploiting a custom-built Fourier-transform imaging spectrometer and the symmetric properties of the Brillouin spectrum, we experimentally demonstrate full-field 2D spectral Brillouin imaging of phantoms as well as biological samples, at a throughput of up to 40,000 spectra per second, with a precision of ~70 MHz and an effective 2D image acquisition speed of 0.1 Hz over a ~300 × 300 µm² field of view. This represents an approximately three-orders-of-magnitude improvement in speed and throughput compared with standard confocal methods, while retaining high spatial resolution and the capability to acquire three-dimensional images of photosensitive samples in biology and medicine.

Kerr microcombs have drawn substantial interest as mass-manufacturable, compact alternatives to bulk frequency combs. This could enable the deployment of many comb-reliant applications previously confined to laboratories. Particularly enticing is the prospect of microcombs performing optical frequency division in compact optical atomic clocks. Unfortunately, it is difficult to meet the self-referencing requirement of microcombs in these systems owing to the approximately terahertz repetition rates typically required for octave-spanning comb generation. In addition, it is challenging to spectrally engineer a microcomb system to align a comb mode with an atomic clock transition with a sufficient signal-to-noise ratio. Here we adopt a Vernier dual-microcomb scheme for optical frequency division of a stabilized ultranarrow-linewidth continuous-wave laser at 871 nm to an ~235 MHz output frequency. This scheme enables shifting an ultrahigh-frequency (~100 GHz) carrier-envelope offset beat down to frequencies where detection is possible and simultaneously placing a comb line close to the 871 nm laser—tuned so that, if frequency doubled, it would fall close to the clock transition in ¹⁷¹Yb⁺. Our dual-comb system can potentially combine with an integrated ion trap towards future chip-scale optical atomic clocks.

Correction to: Nature Photonics https://doi.org/10.1038/s41566-024-01588-8, published online 6 January 2025.

All-perovskite tandem solar cells are promising as next-generation high-efficiency photovoltaic devices. However, further progress in tin-lead (Sn–Pb) mixed perovskites, which are essential as the narrow-bandgap bottom sub-cell, is hampered by unbalanced crystallization processes, leading to inhomogeneous films and reduced power conversion efficiency (PCE). Here we provide a complete understanding of the formation of Sn–Pb films, from the precursor solution to the final film. We find that the total crystallization barrier for Sn-based perovskites is limited by the desorption of dimethyl sulfoxide (DMSO), while Pb-based perovskites experience a smaller DMSO desorption barrier. By engineering the reaction barrier in mixed films via tailoring the DMSO content, we obtain synchronous Sn–Pb perovskite crystallization and high-quality homogeneous films. On the basis of this understanding, we demonstrate single-junction Sn–Pb perovskite solar cells with a PCE of 22.88% and all-perovskite tandem devices with a certified PCE of 28.87%, fabricated by antisolvent-free methods. The unencapsulated tandem devices retain 87% of their initial PCE after about 450 h with maximum power point tracking under 1 sun illumination.

The direct optical transportation of images through multimode fibres (MMFs) is highly sought after in compact photonic systems for MMF-based optical information processing. However, MMFs are highly scattering media, thus degrading information transmitted through them. Existing approaches utilize artificial neural networks or spatial light modulators to reconstruct images scrambled after propagation through the fibre. Despite these advances, achieving direct optical image transportation through MMFs using integrated optical elements with micrometre-scale footprints remains challenging. Here we develop a miniaturized diffractive neural network (DN₂s) integrated on the distal facet of a MMF for the direct all-optical image transportation through the fibre. The DN₂s has a footprint of 150 μm by 150 μm and is fabricated on the facet of a 0.35-m-long MMF using three-dimensional two-photon nanolithography. The fibre-integrated DN₂s enables single-shot optical transportation of images with flat phases in real time for a constant configuration of the MMF. The system achieves a minimum image reconstruction feature size of approximately 4.90 μm over a field of view 65 μm by 65 μm when imaging handwritten digits. Transfer learning is also demonstrated by the direct optical transportation of HeLa cell images projected by spatial light modulators, which were not part of the training dataset. The concept and implementation pave the way to the integration of miniaturized DN₂s with MMFs for compact photonic systems with unprecedented functionalities.