A high-flux entangled-photon source is a key resource for quantum optical study and application. Here, it is realized in a lithium niobate on isolator (LNOI) chip, with 2.79 × ${10}^{11}$ Hz/mW photon-pair rate and 1.53 × ${10}^9$ Hz/(nm mW) spectral brightness. These data are boosted by over 2 orders of magnitude compared with existing technologies. A 160-nm-broad bandwidth is engineered for eight-channel multiplexed energy-time entanglement. Harnessed by high-extinction-frequency correlation and Franson interferences up to 99.17% visibility, such energy-time-entanglement multiplexing further enhances the high-flux data rate and warrants broad application in quantum-information processing on a chip.

Lithium niobate on insulator (LNOI) is a unique platform for integrated photonic applications and especially for high-efficiency nonlinear frequency converters because of the strong optical field confinement. In this work, we fabricated a 6-mm-long periodically poled LNOI ridge waveguide with an optimized duty cycle (50:50) using an active domain structure monitoring method. The performance of the single-pass second-harmonic generation and difference-frequency generation in the nanophotonic waveguide was characterized, and the normalized conversion efficiencies were ∼80% of the theoretical values. These high-quality frequency conversion devices can pave the way for the application of LNOI in nonlinear integrated photonics.

Vectorial structured light with spatially varying amplitude, phase, and polarization is reshaping many areas of modern optics, including nonlinear optics, as diverse parametric processes can be used to explore interactions between such complex vector fields, extending the frontiers of optics to new physical phenomena. However, the most basic nonlinear application (i.e., frequency conversion), still remains challenging for vectorial structured light since parametric processes are polarization dependent, leading to a change in the spatial topological structure of signals. In this work, to break this fundamental limit, we propose a conformal frequency conversion scheme that allows the full spatial structure of vectorial structured light to be maintained in the conversion. We systematically examine its spatial polarization independence based on nondegenerate sum-frequency generation with type-0 phase matching. This proof-of-principle demonstration paves the way for a wide range of applications that require conformal frequency conversion, and, particularly, to implement frequency interfaces with multimodal communications channels, high-dimensional quantum states, and polarization-resolved upconversion imaging.

The rapid developments in orbital-angular-momentum-carrying Laguerre-Gaussian ${\mathrm{(LG}}_l^0)$ modes in recent years have facilitated progress in optical communication, micromanipulation, and quantum information. However, it is still challenging to efficiently generate bright, pure, and selectable ${\mathrm{LG}}_l^0$ laser modes in compact devices. We demonstrate a low-threshold solid-state laser that can directly output selected high-purity ${\mathrm{LG}}_l^0$ modes with high efficiency and controllability. Spin-orbital angular momentum conversion of light is used to reversibly convert the transverse modes inside a cavity and determine the output mode index. The generated ${\mathrm{LG}}_1^0$ and ${\mathrm{LG}}_2^0$ laser modes have purities of approximately 97% and approximately 93% and slope efficiencies of approximately 11% and approximately 5.1%, respectively. Our cavity design can also be easily extended to produce higher-order Laguerre-Gaussian modes and cylindrical vector beams. Such a compact laser configuration features flexible control, low threshold, and robustness, making it a practical tool for applications in superresolution imaging, high-precision interferometers, and quantum correlations.

Electronic processors are reaching the physical speed ceiling that heralds the era of optical processors. Multifunctional all-optical logic gates (AOLGs) of massively parallel processing are of great importance for large-scale integrated optical processors with speed far in excess of electronics, while are rather challenging due to limited operation bandwidth and multifunctional integration complexity. Here we for the first time experimentally demonstrate a reconfigurable all-in-one broadband AOLG that achieves nine fundamental Boolean logics in a single configuration, enabled by ultrabroadband (400–4000 nm) plasmon-enhanced thermo-optical nonlinearity (TONL) of liquid-metal Galinstan nanodroplet assemblies (GNAs). Due to the unique heterogeneity (broad-range geometry sizes, morphology, assembly profiles), the prepared GNAs exhibit broadband plasmonic opto-thermal effects (hybridization, local heating, energy transfer, etc.), resulting in a huge nonlinear refractive index under the order of 10⁻⁴−10⁻⁵ within visual-infrared range. Furthermore, a generalized control-signal light route is proposed for the dynamic TONL modulation of reversible spatial-phase shift, based on which nine logic functions are reconfigurable in one single AOLG configuration. Our work will provide a powerful strategy on large-bandwidth all-optical circuits for high-density data processing in the future.