Nature Photonics最新文献

In contrast to conventional (n–i–p) perovskite solar cells (PSCs), inverted (p–i–n) PSCs offer enhanced stability and integrability with tandem solar cell architectures, which have garnered increasing interest. However, p–i–n cells suffer from energy level misalignment with transport layers, imbalanced transport of photo-generated electrons and holes, and significant defects with the perovskite films. Here we introduce tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane (3TPYMB), a nonionic n-type molecule that, through hydrogen bonding and Lewis acid–base reactions with perovskite surfaces or grain boundaries, enables in situ modulation of perovskite energetics, effectively mitigating the key challenges of p–i–n PSCs. The p–i–n PSCs incorporating 3TPYMB achieve a certified quasi-steady-state power conversion efficiency of 24.55 ± 0.33%, with a reverse scan efficiency of 25.58%. They also exhibit exceptional stability, with unencapsulated devices retaining 97.8% of their initial efficiency after 1,800 h of continuous operation at maximum power point under N₂ atmosphere, 1 sun illumination and 60 °C conditions.

Kerr-induced synchronization (KIS) provides a key tool for the control and stabilization of a dissipative Kerr soliton (DKS) frequency comb, enabled by the capture of a comb tooth by an injected reference laser. Efficient KIS relies on large locking bandwidth, meaning both the comb tooth and intracavity reference power need to be sufficiently large. Although KIS can theoretically occur at any comb tooth, large modal separations from the main pump to achieve large optical frequency division factors are often difficult or unfeasible due to cavity dispersion. While tailoring the dispersion to generate dispersive waves can support on-resonance KIS far from the main pump, this approach restricts synchronization to specific wavelengths. Here we demonstrate an alternative KIS method that allows efficient synchronization at arbitrary modes by multi-pumping a microresonator. This creates a multicolour DKS with a main and an auxiliary comb, the latter enabling the creation of a synthetic dispersive wave. As cross-phase modulation leads to a unique group velocity for both the soliton comb and the auxiliary comb, repetition rate disciplining of the auxiliary comb through KIS automatically controls the DKS microcomb. We explore this colour-KIS phenomenon theoretically and experimentally, showing control and tuning of the soliton microcomb repetition rate, resulting in optical frequency division independent of the main pump noise properties.

An outstanding challenge for deployable quantum technologies is high-resolution laser spectroscopy at the specific wavelengths of ultranarrow transitions in atomic and solid-state quantum systems. Here we demonstrate a highly flexible approach to high-resolution spectroscopy for quantum technologies across a broad range of wavelengths, through the synergistic combination of fine-tooth electro-optic frequency combs and efficient Kerr nonlinear nanophotonics. We show that such fine-tooth combs, which provide simultaneous high spectral and temporal resolution in atomic spectroscopy, undergo coherent spectral translation with essentially no efficiency loss through third-order optical parametric oscillation (OPO) in a silicon-nitride microring. This enables nearly a million comb pump teeth, separated by a 1 kHz spacing, to be translated onto signal and idler beams that can be located across a broad range of wavelengths in the visible and short near-infrared. The generated wavelengths are subject to OPO phase and frequency-matching conditions that are highly controllable through nanophotonic dispersion engineering, and in the current implementation span between 589 and 1,150 nm, with both the electro-optic comb generation process and its spectral translation not introducing appreciable broadening to the pump laser linewidth. We further demonstrate the application of this approach to quantum systems by performing sub-Doppler spectroscopy of the hyperfine transitions of Cs atomic vapour with our electro-optically driven Kerr nonlinear light source. The generality, robustness and agility of our approach, as well as its compatibility with photonic integration, are expected to lead to its widespread applications in areas such as quantum sensing, telecommunications and atomic clocks.

Time-programmable frequency combs enable new measurement paradigms for dual-comb spectroscopy (DCS) that are free of many of the constraints found in traditional DCS. As opposed to fixing the repetition rate offset between combs, free-form DCS uses full control of the temporal offset between the dual-comb pulse trains, thereby enabling user-selectable sampling patterns that optimize resolution, signal-to-noise ratio, species selectivity or acquisition time. Here we show that free-form DCS enables compressive sensing and demonstrate compression factors of up to 155, with an up to 60-fold reduction in acquisition time, while maintaining identical spectral point spacing and comparable signal-to-noise ratio to traditional DCS. We also demonstrate molecular recurrence sampling (an extreme case of compressive sensing) for methane detection at 22× higher sensitivity than traditional DCS at the cost of requiring a priori knowledge of the probed species. Finally, free-form DCS can enable fast species-selective imaging since its radio frequency signal is narrow band, in contrast to traditional DCS, and therefore compatible with limited camera read out rates. We demonstrate imaging of methane plumes across a 128 × 64-pixel focal plane array at a 250 Hz rate. In the future, this flexible free-form approach can enable applications ranging from rapid open-path spectroscopy to nonlinear multidimensional comb-based spectroscopy.

Circularly polarized phosphorescence (CPP) is a spin-forbidden radiative process, and its underlying mechanism is not comprehensively understood, mainly due to the limited examples of efficient triplet emission from small chiral organic molecules with well-defined structures. Here we investigate a pair of chiral enantiomers, R- and S-BBTI, that feature highly distorted spiral ring-locked heteroaromatics with heavy iodine atoms. These chiral molecules are found to exhibit large dissymmetry factors up to 0.013 and emit near-infrared CPP with an efficiency of 4.2% and a lifetime of 119 μs in dimethyl sulfoxide solution excited by ultraviolet irradiation. Their crystals show efficient CPP with 7.0% quantum efficiency and a lifetime of 166 μs. Extensive experimental chiroptical investigations combined with theoretical calculations reveal an efficient spin-flip process that modulates the electron and magnetic transition dipole moments to enhance CPP performance. Moreover, the phosphorescence of R/S-BBTI is oxygen-sensitive and photoactivatable in dimethyl sulfoxide. Therefore, R/S-BBTI can be applied for hypoxia imaging in cells and tumours, expanding the application scope of CPP materials.